VE  G  E  T  A  B  L  E 
F  O  RC I N  G 


RALPH  '.  WATTS 


VEGETABLE 
FORCING 


BY 

RALPH  L.  WATTS 

DEAN  AND  DIRECTOR  OF  THE  SCHOOL  OF  AGRICULTURE  AND 
EXPERIMENT   STATION  OF  THE  PENNSYLVANIA  STATE  COLLEGE 

AND 

AUTHOR  OF  "VEGETABLE  GARDENING,"  A  COMPANION 
VOLUME  TO  THIS  TREATISE 


ILLUSTRATED 


NEW  YORK 

ORANGE  JUDD  COMPANY 
1917 


Copyright,  1917,  by 

ORANGE  JUDD  COMPANY 

All  Rights  Reserved 


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PRINTED  IN  U.  S.  A. 


TO  MY  MOTHER 

MY   FIRST  TEACHER 
IN   VEGETABLE  GARDENING 


PREFACE 


Vegetable  forcing  occupies  an  important  place  in 
American  horticulture.  The  subject  is  taught  to  large 
numbers  of  students,  and  it  has  enlisted  the  interest  of 
thousands  of  gardeners  who  are  attracted  by  the  idea  of 
growing  vegetables  under  artificial  conditions.  To  meet 
the  needs  of  these  two  groups  of  people  has  been  the 
constant  aim  of  the  author. 

The  treatise  is  necessarily  condensed.  It  has  not 
seemed  expedient  to  enter  into  a  lengthy  discussion  of 
subjects  naturally  belonging  to  the  entomologist,  plant 
pathologist,  botanist  or  chemist.  This  would  necessarily 
result  in  the  overlapping  of  college  courses  and  in  trying 
the  patience  of  practical  growers  who  want  merely  a 
working  knowledge  of  the  principles  and  practices  in- 
volved in  the  production  of  the  various  forcing  crops. 

Frequent  visits  have  been  made  to  the  most  important 
vegetable  forcing  centers  of  the  United  States.  Many 
bulletins  of  the  agricultural  experiment  stations  and  of 
the  United  States  Department  of  Agriculture  have  proved 
to  be  of  great  value  as  sources  of  information.  Special 
mention  should  be  made  in  this  connection  of  the  Market 
Growers'  Journal,  and  of  courtesies  extended  by  its  mana- 
ger and  editor,  Sam  W.  Severance. 

The  preparation  of  the  manuscript  would  not  have  been 
possible  without  the  assistance  of  scores  of  friends.  Ex- 
tensive correspondence  was  conducted  with  numerous 
growers,  teachers  and  investigators,  and  I  desire  to  thank 
all  of  these  friends  for  their  most  valuable  co-operation. 

The  author  is  particularly  indebted  to  Prof.  J.  R.  Bech- 
tel  of  The  Pennsylvania  State  College,  and  to  Prof.  C.  W. 


497709 


VI  PREFACE 

Waid  of  the  Michigan  Agricultural  College,  both  of 
whom  read  the  entire  manuscript  and  made  many  valu- 
able suggestions  and  criticisms.  Acknowledgment  is 
also  due  Dr.  William  Frear  of  The  Pennsylvania  State 
College  for  assistance  in  connection  with  the  chapter  on 
Mushrooms,  and  to  Mr.  Harold  Ware,  a  practical  and 
scientific  grower  of  mushrooms,  who  made  many  timely 
comments  on  this  subject;  to  Dr.  C.  W.  Stoddart  of  The 
Pennsylvania  State  College  for  reading  the  section  on 
fumigation  with  hydrocyanic  gas;  to  Prof.  J.  F.  Adams 
of  The  Pennsylvania  State  College,  who  read  the  notes  on 
diseases  affecting  lettuce,  tomato  and  cucumber;  to  Prof. 
R.  W.  DeBaun  of  Rutgers  College  and  B.  C.  Haines  of 
Norfolk,  Virginia,  for  data  furnished  relating  to  culture 
of  frame  crops;  and  to  Miss  Julia  C.  Gray  for  editorial 
services. 

Most  of  the  illustrations  were  made  by  the  author  upon 
visits  to  commercial  establishments,  and  we  gratefully 
acknowledge  the  courtesies  extended  in  this  connection 
by  a  large  number  of  growers,  including  M.  L.  Ruetenik, 
Cleveland,  Ohio;  Searles  Brothers,  Toledo,  Ohio; 
Chauncey  West,  Irondequoit,  N.  Y. ;  Dunbar  and  Hop- 
kins, Ashtabula,  Ohio;  J.  H.  Rice,  Ashtabula,  Ohio;  R. 
Hittinger,  Belmont,  Mass. ;  Wyman  Brothers,  Arlington, 
Mass. ;  F.  J.  Zuck,  Erie,  Pa. ;  W.  H.  Weinschenk,  New 
Castle,  Pa. ;  H.  H.  Mishler,  Johnstown,  Pa. ;  and  others. 

We  are  indebted  to  Kroeschell  Bros.  Co.,  Chicago,  Til., 
for  illustrations  Nos.  1,  148  and  149 ;  to  H.  F.  Tompson, 
Arlington,  Mass.,  for  illustration  No.  2;  to  "Lord  and 
Burnham  Company,  New  York  City,  for  illustration 
No.  8;  to  Hitchings  &  Company,  New  York  City,  for 
illustration  No.  10;  to  John  A.  Evans  Company,  Rich- 
mond, Ind.,  for  illustration  No.  19;  to  Skinner  Irri- 
gation Co.,  Troy,  Ohio,  for  illustrations  No.  26  and  54 ;  to 
R.  W.  De  Baun  of  Rutgers  College  for  illustrations  Nos. 
27,  133,  135,  140,  141,  143,  144  and  145 ;  to  C.  O.  Jclliff 


PREFACE  Vll 

Mfg.  Company,  Southport,  Conn.,  for  illustration 
No.  28;  to  C.  B.  Sayre  of  Purdue  University  for  illustra- 
tions Nos.  29,  68,  81,  136,  137  and  138 ;  to  the  Bureau  of 
Plant  Industry  for  illustrations  Nos.  35  and  36;  to  the 
United  States  Department  of  Agriculture  for  illustration 
No.  39 ;  to  the  Ohio  Agricultural  Experiment  Station  for 
illustration  No.  53;  to  E.  F.  Stoddard  of  the  Maryland 
Agricultural  College  for  illustration  No.  66 ;  to  the  Ten- 
nessee Experiment  Station  for  illustrations  Nos.  76  and 
77 ;  to  Sutton  and  Sons  of  Reading,  England,  for  illustra- 
tions Nos.  80,  92,  125  and  126;  to  G.  L.  Tiebout  of  the 
Louisiana  College  of  Agriculture  for  illustration  No.  84 ; 
to  David  Lumsden  formerly  of  New  Hampshire  College, 
now  of  Cornell  University,  for  illustrations  Nos.  91,  95  and 
104;  to  L.  M.  Montgomery  of  Ohio  State  University  for 
illustrations  Nos.  127  and  129;  to  W.  H.  Weinschenk  of 
New  Castle  for  illustration  No.  134;  to  the  Virginia 
Truck  Experiment  Station  for  illustration  No.  139;  and 
to  C.  G.  Woodbury  of  Purdue  University  for  illustration 
No.  146. 


CONTENTS 

Pages 

CHAPTER  I 
A  GENERAL  VIEW 1 

Vegetable  forcing — The  history  of  vegetable  forcing 
— Prominent  sections — Importance  of  vegetable  forcing 
— Types  of  vegetable  forcing — Organization — Southern 
competition — The  superior  quality  of  greenhouse  vege- 
tables— Economic  production — Capital  required — Profits 
— Location — Climatic  influences — Relative  importance  of 
forcing  crops — The  outlook. 

CHAPTER  II 

GREENHOUSE  CONSTRUCTION  AND  HEATING  __• . 13 

Greenhouses  vs.  frames — Site  and  position  of  house — 
Grading  —  Size  and  proportions — Materials — Arrange- 
ment of  houses — Forms  of  greenhouses — Wood  con- 
struction— Semi-iron  construction — Iron  construction — 
Truss  construction — Walls — Frame — Wall  plate  or  sill 
—The  eaves  or  side  plates — Sash-bars — Roof — Venti- 
lators— Posts,  purlins  and  braces — Doors — Glass — Glaz- 
ing —  Shading  —  Painting  —  Beds  and  benches  — Walks, 
alleys  and  roadways — Steam  vs.  hot  water  heating — 
Radiation  required — Systems  of  hot  water  heating — 
Systems  of  steam  heating — Location  of  pipes — The 
boiler — Thermostats. 

CHAPTER  III 
SOILS    47 

Selection — Greenhouse  soils  abnormal — Texture — Struc- 
ture— Color — Organic  content — Water  content — Chemi- 
cal composition — Depth — Drainage — Muck  soil — Boston 
soils — Chester  fine  sandy  loam — Ashtabula  soils — Cleve- 
land soils — Toledo  soils — Lansdale  silt  loam — Norfolk 
series — Irondequoit  soils — Soil  adaptation. 

CHAPTER  IV 

MANURES,  LIME  AND  FERTILIZERS 59 

Need  of  plant  food — Value  of  manures — Rhode  Island 
IX 


X  CONTENTS 

experiments  —  Horse  manure  —  Cow  manure  —  Sheep 
manure — Poultry  manure — Rate  of  application — Liquid 
manure — The  functions  of  lime — Commercial  fertilizers 
— Sources  of  nitrogen — Sources  of  phosphoric  acid — 
Sources  of  potash. 

CHAPTER  V 

SOIL   PREPARATION   70 

Ideal  conditions — Changing  soils — Composting — Manur- 
ing in  the  field — Green  manuring — Manuring  in  the 
greenhouse — Drying  greenhouse  soils — Summer  mulch- 
ing—  Plowing  and  harrowing — Spading  and  raking  — 
Applying  lime — Applying  fertilizers. 

CHAPTER  VI 
SOIL  STERILIZATION  85 

The  necessity  of  sterilization — Methods — Steam  steri- 
lization— Temperature  required — Time  required — Boiler 
and  pressure — Preparing  soil — Devices  for  sterilizing — 
Boxes — Pans — Perforated  pipe — Perforated  pegs — Tile 
— Frequency  of  sterilization — After  treatment — Forma- 
lin sterilization — Strength  of  solution — Application — 
Cost — Hot  water  sterilization 

CHAPTER  VII 

INSECT  ENEMIES  AND  THEIR  CONTROL 103 

The  insect  problem — Preventive  measures — The  rotation 
of  crops — Steam  sterilization — Tobacco  fumigation — 
Tobacco  preparations  —  Hydrocyanic  gas  fumigation  — 
Miscellaneous  insecticides — The  spraying  apparatus  — 
Nematodes  (Heterodera  radicicola) — Aphis — White  fiy 
(Aleyrodes  vaporariorum) — Appearance  of  infested 
plants — Red  spider  (Tetranychus  telarius,  Linn). 

CHAPTER  VIII 

DISEASES  AND  THEIR  CONTROL 127 

An  important  factor — Sanitation — Soil  selection — Ma- 
nure selection — Infected  plants — Influence  of  light — In- 
fluence of  moisture — Influence  of  temperature — Vigor 
of  growth — Crop  rotation — Resistant  varieties  or  strains 
— Steam  sterilization — Formalin  sterilization — Summer 
mulch  —  Spraying  —  Bordeaux  mixture  —  Ammoniacal 
copper  carbonate — Potassium  sulphide  or  liver  of  sul- 
phur— Sulphur. 


CONTENTS  XI 

CHAPTER  IX 
STARTING   PLANTS   134 

Plants  of  high  quality — Seed  of  high  quality — Separate 
plant  houses — Flats  vs.  beds — Use  of  pots — Soil  selec- 
tion and  preparation — Seed  sowing — Transplanting  — 
Care  of  plants — Damping-off. 

CHAPTER  X 

WATERING,  HEATING,  VENTILATING  AND  SHADING 149 

Importance  of  water  —  Amount  of  water  required  — • 
When  to  water — Temperature  of  water — Methods  of 
watering  — Watering  can  and  hose  —  Sub-irrigation  — 
Overhead  irrigation  — Temperature  — Ventilation  — 
Shading. 

CHAPTER  XI 
MARKETING 165 

Psychology  of  successful  salesmanship — Harvesting — 
Packing  room — Packages — Preparation  for  market  — 
Packing — Methods  of  selling  —  Delivery  trucks  and 
wagons — Refrigeration — Pre-cooling— Advertising — Co- 
operative associations. 

CHAPTER  XII 
ASPARAGUS   177 

Importance — Principles  involved  — Varieties — Growing 
the  roots  or  crowns — Digging  and  storing  roots — Forc- 
ing in  permanent  beds — Forcing  transplanted  roots — 
Soil — -Planting  — Temperature  — Watering — Marketing. 

CHAPTER  XIII 
RHUBARB    190 

Importance — Quality — Light  —  Principles  —  Forcing  in 
permanent  beds — Forcing  transplanted  roots — Varieties 
— Growing  roots — Digging  and  storing  roots — Preparing 
beds — Freezing  roots — Planting — Watering  — Tempera- 
ture— Harvesting  and  marketing — Yields  and  returns. 

CHAPTER   XIV 
LETTUCE    204 

Importance — Quality — Beds  vs.  benches — Varieties — 
Seed — Soil — Fertilizing — Preparation  of  soil — Starting 
plants — Planting  distances — Planting — Watering — Tern- 


Xll  CONTENTS 

perature  —  Ventilation  —  Cultivation  —  Intercropping  — 
Frame  culture — Pot  culture — Insect  enemies — Diseases 
— Electro-culture — Harvesting — Marketing — Yields  and 
returns. 

CHAPTER  XV 

CAULIFLOWER 234 

History  —  Importance  —  Beds  vs.  benches  — Varieties — 
Seed — Soil — Fertilizing — Soil  preparation — Starting  the 
plants — Planting — Intercropping — Watering — Tempera- 
ture— Ventilation — Cultivating — Insect  enemies — Dis- 
eases— Frame  culture — Head  protection — Marketing. 

CHAPTER  XVI 
RADISH    246 

Importance — Light — Beds  vs.  benches — Varieties — Soil 
— Fertilizing — Soil  preparation — Seed — Sowing  — Thin- 
ning—  Intercropping — Watering — .Temperature — Venti- 
lation— Cultivation — Enemies — Frame  culture — Market- 
ing— Yields  and  returns. 

CHAPTER  XVII 
TOMATO   260 

History — Importance — Pots  and  boxes — Benches  vs. 
ground  beds — Varieties — Soil — Fertilizing — Soil  prepa- 
ration— Seed — Cuttings — Starting  plants — Planting  dis- 
tances— Planting — Intercropping — Training —  Watering 
— Temperature — Ventilation — Cultivation  —  Mulching — 
— Pollinating  — Insects — Diseases — Leaf  mold — Blossom 
end  rot — Leaf  spot  or  leaf  blight — Alternavia  Solani — 
— Marketing — Yields  and  returns. 

CHAPTER  XVIII 
CUCUMBER  300 

History — Importance — Season  of  culture — Ground  beds 
vs.  raised  benches — Varieties — English  varieties — Ameri- 
can varieties — American  English  crosses — Seed — Start- 
ing the  plants  —  Soil  —  Fertilizing  —  Soil  preparation — 
Planting  distances— Planting— Watering—  Cultivation- 
Mulching — Temperature — Shading — Ventilation — Train- 
ing and  pruning—  Pollinating—  Intercropping—  Frame 
culture — Insect  enemies — Diseases — Marketing —  Yields 
and  returns. 

CHAPTER   XIX 

MUSKMELON    346 

Importance — House — Varieties — Starting  plants — Soil — 
Fertilizing — Soil  preparation — Watering — Temperature 


CONTENTS  Xlll 

Training —  Pollinating —  Ventilation  — Insect  enemies — 
Diseases — Yields  and  size  of  fruit. 

CHAPTER  XX 

MISCELLANEOUS  VEGETABLES 356 

Bean — Beet — Carrot — Chinese  cabbage — Cress — Celery — 
Dandelion — Eggplant — Kohl-rabi  —  Mints  —  Mustard  — 
Onion — Parsley — Pea — Pepper — Sea  kale  —  Spinach  — 
Swiss  chard — Turnip — Witloof  chicory. 

CHAPTER  XXI 
SYSTEMS  OF  CROPPING 379 

Necessity  of  intensive  methods — Selection  of  crops — 
Single  cropping — Succession  cropping — Succession  crop- 
ping plans — Companion  cropping. 

CHAPTER  XXII 
FRAME   CROPS    387 

Frames  vs.  greenhouses — Importance  of  frame  forcing 
— Location  of  frames — Construction  of  frames — Cloth  - 
.  covered  frames — Sash-covered  frames — Mats  and  shut- 
ters— Heating  frames — Fertilizing — Watering — Ventila- 
tion— Control  of  pests — Vegetables  grown  in  frames : 
Asparagus  —  Bean  —  Beet  —  Carrot  —  Cauliflower — 
Celery —  Chinese  cabbage  —  Corn  salad  —  Cress  —  Cu- 
cumber— Dandelion — Eggplant —  Kohl-rabi —  Lettuce — 
Muskmelon —  Mustard —  Onion  —  Parsley  —  Pepper — 
Radish — Rhubarb —  Spinach —  Swiss  chard —  Turnips — 
Witloof  chicory. 

CHAPTER  XXIII 
MUSHROOMS  407 

Importance — Botanical  characteristics — Where  to  grow 
mushrooms — Material  for  beds — Preparation  of  beds — 
Spawn — Spawning  the  beds — Casing  the  beds — Tempera- 
ture— Light — •  Insect  enemies — Diseases — Picking  and 
marketing — Yields  and  prices — Food  value — Value  of 
manure  from  mushroom  beds. 


LIST  OF  ILLUSTRATIONS 


Fig.  Page 

1.  A  modern  range  of  houses  at  Toledo,  Ohio 14 

2.  Typical  three-quarter-span  houses  of  the  Boston  district  15 

3.  Two-acre   three-quarter-span   hillside   house   near    New 

Castle,  Pa.   16 

4.  Boiler  room  and  packing  house  of  a  ten-acre  range  near 

Toledo,  Ohio - 17 

5.  Wide  corridor  in  a  Toledo,  Ohio,  range 19 

6.  Typical  even-span  range  of  narrow  units 20 

7.  Even-span  houses  with  continuous  ventilators 21 

8.  Lean-to  house.     Note  protected  frames 23 

9.  A  modern  steel-frame  house.    Note  large  door 24 

10.  A  satisfactory  type  of  semi-iron  construction 25 

11.  A  house  of  truss  construction 26 

12.  Semi-iron  construction,  showing  posts  and  purlin  sup- 

ports set  in  concrete 27 

13.  A  common  form  of  wood  wall  sill 28 

14.  Iron  eave  plate.     Note  roof  bar  and  post  bracket 28 

15.  Wooden  gutter   29 

16.  Iron  gutter  with  roof  bars  connected.    Also  shows  con- 

nections with  iron  post 29 

17.  (a)  Typical  roof  bar.     (b)  Typical  end  bar 30 

18.  Semi-iron  house.     Note  large  door  and  ventilators  on 

sides  and  end 31 

19.  A  satisfactory  machine  for  operating  ventilators 32 

20.  A  corridor  leading  to  the  packing  room  in  a  large  range  33 

21.  Bench  with  pipe-frame  support 34 

22.  Concrete  pillars  for  bench  supports 35 

23.  Walk  with  concrete  sides.     Peerless  tomato  in  an  Iron- 

dequoit    (New  York)    house 37 

24.  An  alley  of  liberal  width  in  a  cucumber  house 41 

25.  Roadway  in  a  two-acre  house :  45 

26.  Manure  spreaders,  plows  and  harrows  are  often  used  in 

modern  houses  61 

27.  Manure    is   usually    placed   in   compost   piles   near    the 

houses.     (In  this  instance,  mushroom  houses) 71 

28.  Small  smoothing  harrow 83 

29.  Pan  steam  sterilization  in  operation  at  the  Indiana  Agri- 

cultural Experiment   Station 86 

30.  A  portable  steam  engine  may   be   used   for  sterilizing 

small  houses   94 

XV 


XVI  LIST  OF  ILLUSTRATIONS 

Fig.  Page 

31.  Peg  or  rake  steam  sterilizer  used  by  some  growers  at 

Toledo,  Ohio 95 

32.  Peg  steam  sterilizer  in  operation  at  Toledo,  Ohio 97 

33.  Apparatus  for  formalin   sterilization.      (W.   T. — Water 

Tank.  F.  T. — Formalin  Tank.  G. — Waterglass  gauge 
to  show  quantity  of  formalin.  A. — Air  cock.  V. — 
Valve.  F. — Funnel.  E. — Air  pipe  to  maintain  same 
pressure  in  both  tanks.  D. — Drain-off  cock.  H.  and 
R— Supports.  B.— Base.  O—  Outlet.  S.— Glass  tube 
through  which  the  formalin  drops  to  tank  below 98 

34.  Garbage  can  suspended  to  wire,  used  in  fumigating  with 

tobacco  stems   107 

35.  Female  nematode   (Heterodera  radicicola)    magnified  85 

diameters;  a,  mouth;  b,  spherical  sucking  bulb;  c, 
ovaries  as  seen  through  the  body  wall;  d,  anus;  e, 
small  white  spots  showing  approximately  the  natural 
size  of  these  worms.  They  are  usually  white.  It  is 
generally  not  difficult  to  isolate  them  in  water  by 
breaking  open  the  galls  containing  them.  (After 
N.  A.  Cobb) 113 

36.  Male  nematode:    I,  Worm  in  profile  view;    II,  head  of 

the  same,  more  highly  magnified;  III,  middle  region 
of  the  worm,  showing  blind  ends  of  the  sexual 
organs;  IV,  posterior  extremity.  The  drawings  were 
prepared  from  stained  specimens,  examined  in  car- 
bolic acid  solution,  a,  lips ;  b,.  cesophageal  tube ;  c, 
median  bulb;  d,  excretory  pore;  e,  spear;  f,  intes- 
tine ;  g,  blind  ends  of  testicles ;  h,  testicles ;  i, 
spicula;  j,  rudimentary  bursa;  k,  anus.  (After 
N.  A.  Cobb) 114 

37.  Galls  on  cucumber  roots  produced  by  nematodes 115 

38.  Roots  of  tomato  plant  completely  invaded  by  gallworms. 

(After  George  F.  Atkinson) 116 

39.  Galls  on  lettuce  roots  caused  by  nematodes 118 

40.  White  fly  (Aleyrodes  vaporariorum)  :    a,  egg;   b,  young 

larva;  c,  pupa,  top  view;  d,  pupa,  side  view;  e, 
adult — c,  d,  e,  about  25  times  natural  size ;  a,  b,  still 
more  enlarged  (a-d,  after  Morrill,  Tech.  Bui.  Mass. 
Exp.  Sta. ;  e,  original) 111) 

41.  Two  nurseries  in  a  four-acre  Boston  range.     Note  let- 

tuce seedlings  of  different  sizes 134 

42.  Nursery   in   large    range    near    Boston.      Head    lettuce 

plants   135 

43.  Flat  of  Grand  Rapids  lettuce  seedlings 136 

44.  Flat  of  lettuce  plants  ready  for  transplanting  into  the 

beds    137 


LIST  OF  ILLUSTRATIONS  XV11 

Fig.  Page 

45.  Lettuce  plants  in  flats 138 

46.  Utilizing  shelf  space  in  an  overcrowded  house.     Unfair 

to  the  plants  in  the  beds  underneath 139 

47.  Flat  with  wire  mesh  bottom 140 

48.  Cucumber  plants  growing  in  pots  and  in  an  adjacent  bed  141 

49.  Potted  cucumber  plants  in  a  bed  of  gladioli 143 

50.  Chamber  used  for  the  steam  sterilization  of  soil  in  flats. 

(Note  that  the  flats  are  on  carts) 144 

51.  Spotting  board  used  in  transplanting  lettuce 147 

52.  A  convenient  form  of  nozzle  for  greenhouse  watering—  154 

53.  Tile  laid  in  bed  for  sub-irrigation 157 

54.  Overhead  irrigation  in  a  lettuce  house 159 

55.  A  convenient  homemade  cart  for  handling  two  barrels  at 

a  time   167 

56.  A  handy  cart  for  greenhouse  use 168 

57.  Harvesting  a  crop  of  cucumbers  in  a  large  range 170 

58.  Corner  of  packing  room  in  a  well-managed  establish- 

ment    171 

59.  A  load  of  cucumbers  en  route  to  shipping  station 173 

60.  A  large  root  of  asparagus  suitable  for  forcing  purposes  178 

61.  Graph  showing  returns  from  asparagus  roots  of  differ- 

ent sizes   181 

62.  Rhubarb  stalks  grown  from  roots  planted  in  coal  ashes  192 

63.  Rhubarb  growing  in  coal  ashes  in  "an  ordinary  cellar 193 

64.  Rhubarb  growing  in  a  coldframe 195 

65.  An  inexpensive  rhubarb  house  near  Boston.     Sash  are 

placed  on  the  frame  whenever  it  is  desired  to  force 

the   crop   196 

66.  A  simple  house  in  Maryland  for  the  forcing  of  rhubarb  197 

67.  A  large  rhubarb  root  suitable  for  forcing 198 

68.  Rhubarb  forced  in   almost  total  darkness.     Note  small 

leaf  blades  201 

69.  Head  lettuce  in  the  Boston  district 206 

70.  Grand  Rapids  lettuce  in  a  large  Middle  West  range 207 

71.  Cos  lettuce  on  the  right;    head  lettuce  on  the  left 208 

72.  Pot  experiment  at  the  Pennsylvania  State  College,  show- 

ing the  value  of  lime  for  lettuce 214 

73.  Transplanting    board    used    for    setting    lettuce.      Note 

large  pegs 218 

74.  Plants  of  same  age.     One  on  left  dwarfed  because  the 

tap  root  was  bent  when  the  plant  was  set  in  the  bed —  219 

75.  The  lettuce  in  this  large  range  is  cultivated  with  a  5- 

pronged  weeder  attached  to  a  long  handle 221 

76.  Pot-grown  plant  ready  to  set  in  the  bed 223 

77.  Pot-grown  plant  ready  for  market 224 

78.  Grand    Rapids   lettuce 229 

79.  A  basket  of  lettuce  ready  for  market 231 


XVIII  LIST  OF  ILLUSTRATIONS 

Fig.  Page 

80.  Choice  head  lettuce  grown  in  England 232 

81.  Cauliflower.    Almost  every  plant  produced  a  head 235 

82.  A  typical  head  of  greenhouse-grown  cauliflower 236 

83.  Vigorous  cauliflower  plants  are  essential  to  success 240 

84.  Cauliflower   trimmed    for    market.      Head    on    extreme 

right  trimmed  very  short 244 

85.  Tomatoes  in  a  Kennett  Square  (Pa.)  house 263 

86.  Bonny  Best  tomato 268 

87.  Comet  tomato   269 

88.  Globe  tomato   270 

89.  Peerless  tomato 271 

90.  A  good  crop  of  greenhouse  tomatoes 273 

91.  Eclipse   X  Earliana  tomatoes   at   the   New   Hampshire 

Experiment  Station 277 

92.  A  house  of  plants  growing  in  pots — England 281 

93.  Blossom  end  rot  of  tomato 293 

94.  A  convenient  picking  basket 295 

95.  Each  paper  box  holds  six  pounds  of  tomatoes,  and  eight 

boxes  may  be  packed  in  a  standard  bushel  box,  such 

as  is  used  in  the  Boston  district 296 

96.  Tomatoes  are   sometimes  wrapped  and  packed    in   the 

manner  shown  in  this  illustration 297 

97.  A  unique  way  of  packing  a  number  of  small  boxes  of 

tomatoes    298 

98.  The  Boston  bushel  box,  showing  the  upper  tier  of  six- 

pound  packages  299 

99.  English  cucumbers  in  an  English  house 301 

100.  Good  specimens  of  White  Spine  cucumber 303 

101.  The  long  cucumber   at  the  left  is  English   Telegraph. 

The  short  one  at  the  right  is  a  strain  of  White  Spine. 
The  middle  specimen  is  Abundance — a  cross  between 

the  other  two  varieties 304 

102.  Arlington  White  Spine  cucumber 305 

103.  Rawson  Hothouse  cucumber 306 

104.  White  Spine  cucumber.     The  left  specimen  is  of  much 

better  form  at  stem  end 307 

105.  Davis  Perfect  from  the  originator 308 

306.    Abundance  from  the  originator 309 

107.  Cucumber  seed  production  house 310 

108.  Special  White  Spine  cucumbers  grown  for  seed 311 

109.  A  cucumber  nursery  in  the  Boston  district 312 

110.  Cucumbers  showing  upright  training 313 

111.  Cucumbers  and  narrow  strips  for  their  support 315 

112.  Single  stem  cucumber  training.    Note  how  the  plant  has 

been  twined  about  the  string 316 

113.  Cucumbers  trained  on  A-form  trellis 319 

114.  Abundance  cucumber  and  arbor  form  of  training 323 


LIST  OF  ILLUSTRATIONS  XIX 

Fig.  Page 

115.  Abundance    cucumber    and    arbor    form    of    training. 

Season  well   advanced 327 

116.  Single    stem    training   of    cucumber.    Note   location   of 

male  and  female  flowers  and  the  small  nickles 329 

117.  Branch  of  cucumber  showing  male  and  female  flowers. 

The  latter  may  be  recognized  by  the  miniature  pickles  330 

118.  Hive  of  bees  at  end  of  greenhouse 333 

119.  Box  containing  several  hives  of  bees 334 

120.  Three  grades  of  cucumbers 341 

121.  Cucumbers  packed  in  barrels 343 

122.  Cucumbers  packed  in  bushel  boxes 344 

123.  Cucumbers  packed  in  half-bushel  basket 345 

124.  Muskmelons  grown  at  the  New  Hampshire  Experiment 

Station.    Note  thin  strips  of  wood  which  support  the 

fruit — — 349 

125.  Muskmelons  growing  in  an  English  house 353 

126.  Pole  beans  growing  in  an  English  house 358 

127.  Chinese   cabbage    361 

128.  Dandelion  being  forced  in  a  cheap  house  near  Boston—  364 

129.  Kohl-rabi  at  the  Ohio  State  University 367 

130.  Witloof  chicory 374 

131.  Planting  witloof  chicory  in  trenches 377 

132.  Well-protected  wooden   coldframes 388 

133.  An  extensive  flat  of  coldframes.     Note  method  of  ven- 

tilation and  sideboards  nailed  to  stakes 389 

134.  Coldframes  well  protected  by  the  greenhouse.    Note  rye 

straw  mats 391 

135.  Frame  cauliflower  following  a  companion  crop  of  let- 

tuce. Note  mats,  which  are  being  thoroughly  dried 
before  they  are  stored  for  the  summer 393 

136.  Surface   hotbed.      Note   notched   block    for    supporting 

sash    394 

137.  Pit  for  hotbed  showing  drainage  basin 395 

138.  An  extensive  flat  of  coldframes.     Note  method  of  ven- 

tilation and  irrigating  lines 397 

139.  A  coldframe  plat  near  Norfolk,  Va.     Note  method  of 

ventilating    398 

140.  Frame  crop  of  Nantes  carrot 399 

141.  Frame  cauliflower  ready  to  head 400 

142.  Frame  cucumbers  near  Norfolk,  Va 401 

143.  Soil    in    coldframes,    after    sowing    seed    of    dandelion, 

carrot,  parsley,  etc.,  for  the  fall  crop,  is  covered  with 
salt  hay  to  conserve  moisture  and  to  prevent  the  soil 
from  baking.  When  seedlings  are  up,  the  hay  is 
removed  402 

144.  Coldframes  ready  for  seeding  in  August  with  carrots 

and  other  fall  crops 403 


XX  LIST  OF  ILLUSTRATIONS 

Fig.  Page 

145.  Choice  heads  of  lettuce  saved  for  the  production  of  seed  404 

146.  Double  frames  are  sometimes  used  for  forcing  purposes  405 

147.  Wooden  mushroom  houses  at  Kennett  Square,  Pa. 408 

148.  A    modern    commercial    mushroom    range    at    Kennett 

Square,  Pa.     Built  of  concrete  and  tile.    Frost  proof 

and  fire  proof 409 

149.  A    New    Jersey    double    duty    house.      Mushrooms    are 

grown   in  the  cellar,  and  plants   and  flowers  in  the 

greenhouse  above 410 

150.  Mushroom  beds  in  a  modern  house 411 

151.  Composting  manure  for  the  growing  of  mushrooms 412 

152.  Drying  bricks  of  mushroom  spawn 415 

153.  A  good  crop  of  mushrooms 418 

154.  A  morning's  picking.     Note  variation  in  size 421 

155.  Baskets  of  mushrooms  packed  ready  for  the  covers____  422 

156.  A  wagonload  of  mushrooms  en   route  to   the   shipping 

station    423 


CHAPTER  I 
A  GENERAL  VIEW 

Vegetable  forcing  is  an  important  branch  of  vegetable 
gardening  or  olericulture.  It  relates  to  the  growing  of 
vegetables  to  maturity  or  to  edible  size  in  greenhouses, 
hotbeds,  coldframes,  or  other  special  structures.  The 
cultural  conditions  are  usually  artificial  throughout  the 
growing  period,  although  there  are  exceptions,  as  when 
lettuce  is  planted  in  frames  during  the  spring  season  and 
the  glass  dispensed  with  for  a  few  weeks  previous  to  the 
harvesting  of  the  crop.  Of  the  various  branches  of  oleri- 
culture, vegetable  forcing  is  the  most  intensive  and  the 
most  highly  specialized.  The  cultural  conditions  must  be 
created  and  kept  under  absolute  control,  in  order  that  the 
best  results  may  be  realized.  Because  of  this  possibility, 
vegetable  forcing  is  often  regarded  as  the  most  certain  or 
most  reliable  branch  of  vegetable  gardening. 

The  history  of  vegetable  forcing  in  the  United  States 
began  with  the  use  of  hotbeds  by  the  pioneer  gardeners. 
Hotbeds  were  employed  mainly  for  the  starting  of  the 
early  plants,  although  growers  found  it  profitable  to 
mature  some  crops,  especially  lettuce  and  radishes,  in 
hotbeds  heated  by  manure.  Previous  to  1880  very  few 
greenhouses  were  devoted  to  vegetable  forcing,  and  their 
use  for  that  purpose  at  all  was  very  infrequent  until  1888. 
The  first  houses  were  low  and  narrow — mere  toyhouses 
as  compared  with  our  modern  structures  covering  acres 
of  ground.  Houses  11  feet  wide  and  about  100  feet  long 
were  common,  and  later  some  were  built  that  measured 
20  or  22  feet  in  width  and  more  than  100  feet  in  length. 

Vegetable  forcing,  however,  was  not  of  great  commer- 
cial importance  until  after  1890,  and  the  industry  has 


e  c     £ ;  e *e c.* ?  <        t      a      « <: 
2  ;  ;    ::  j  ^VEGETABLE  FORCING 

made  its  greatest  and  most  rapid  development  since  1900. 
In  1894,  Taft  called  attention  to  a  house  near  Arlington, 
Mass.,  which  up  to  that  time  was  probably  the 
largest  ever  erected  for  the  forcing  of  vegetables.  It  was 
33  feet  wide,  370  feet  long,  and  covered  nearly  one-third 
of  an  acre.  In  1912  a  range  of  the  ridge  and  furrow  type 
that  covered  10  acres  was  completed  at  Toledo,  Ohio. 

Three  men  were  particularly  prominent  in  connection 
with  the  early  history  of  vegetable  forcing.  No  one  did 
so  much  to  encourage  the  growing  of  crops  in  frames  and 
in  inexpensive  greenhouses  as  Peter  Henderson.  He 
taught  both  by  example  and  by  writing,  and  his  books 
are  so  practical  that  they  are  still  greatly  prized  by  vege- 
table growers.  In  New  England,  W.  W.  Rawson  exerted 
a  great  influence  on  greenhouse  production.  He  was  one 
of  the  first  to  construct  greenhouses  for  the  forcing  of 
vegetables,  and  he  was  especially  prominent  because  he 
built  and  advocated  the  building  of  greenhouses  of  larger 
proportions  than  were  known  previous  to  1894.  His 
writings  were  also  valuable  in  promoting  the  industry. 

In  the  West,  Eugene  Davis  has  been  one  of  the  most 
prominent  figures  in  this  industry.  He  has  been  the 
leader  at  Grand  Rapids ;  his  first  houses  were  built  in 
1876  and  others  were  added  to  his  range  as  market  de- 
mands increased.  These  were  probably  the  first  vege- 
table forcing  houses  built  in  the  Middle  West.  For  many 
years,  Grand  Rapids  supplied  practically  all  the  green- 
house produce  that  was  consumed  by  the  large  cities  of 
the  Middle  West.  Mr.  Davis  is  best  known  as  the 
originator  of  the  famous  Grand  Rapids  lettuce  and  the 
Davis  Perfect  cucumber. 

Prominent  sections. — Boston  occupies  first  place  in  the 
commercial  importance  of  its  vegetable-forcing  interests. 
Most  of  the  houses  are  located  in  suburban  towns, 
Arlington  and  Belmont  being  the  most  important.  In 
1912,  there  were  16  establishments  of  two  acres  or  more, 


A   GENERAL  VIEW  3 

and  some  of  the  ranges  covered  four  acres  of  land.  This 
district  then  had  about  60  acres  of  glass  devoted  ex- 
clusively to  vegetable  forcing. 

There  are  more  acres  of  glass  devoted  to  this  industry 
in  Ohio  than  in  any  other  state.  In  1912  Toledo  had 
about  40  acres  under  glass,  one  of  the  ranges  covering  10 
acres;  Cleveland  had  about  25  acres  and  Ashtabula 
probably  an  equal  area.  There  are  large  houses  at 
Newark,  Columbus,  Cincinnati,  Lancaster  and  many 
other  smaller  cities  and  towns.  It  is  estimated  that,  in 
1912,  about  140  acres  of  glass  were  used  in  Ohio  for  the 
forcing  of  vegetables.  Greenhouse  building  has  been 
active  in  some  of  these  sections  since  the  1912  estimates 
were  made. 

Although  there  are  some  spacious  houses  at  various 
places  in  Michigan,  Grand  Rapids  is  the  most  important 
center.  This  district  had  from  35  to  40  acres  of  vegetable- 
forcing  houses  in  1912,  and  one  establishment  covered 
over  four  acres  of  land. 

Irondequoit,  New  York,  is  well  known  for  its  large 
number  of  houses  of  medium  size.  No  establishment  in 
this  district  contains  more  than  four  acres,  and  most  of 
the  ranges  cover  less  than  one  acre.  There  were  65 
houses  in  1912  within  a  radius  of  three  miles,  and  they 
included  a  total  area  of  about  25  acres,  so  that  the  average 
is  less  than  one-half  of  an  acre.  They  are  almost  invari- 
ably operated  in  connection  with  market  gardens,  and 
are  of  great  value  in  the  starting  of  early  plants. 

There  are  many  vegetable-forcing  establishments  in 
Pennsylvania,  although  less  progress  has  been  made 
there  than  in  several  other  states.  The  industry  is  most 
prominent  at  New  Castle,  Erie,  Altoona  and  Kennett 
Square. 

In  Illinois  there  are  large  ranges  at  Chicago,  Aurora, 
Streator,  Morrison  and  other  points.  There  are  many 
extensive  establishments  in  Indiana,  Iowa,  Minnesota, 


4  VEGETABLE  FORCING 

New  Jersey  and  other  states.  There  are  also  large  vege- 
table-forcing establishments  in  Canada. 

The  hotbed  and  frame  industries  of  the  country  should 
also  be  considered  in  this  connection.  All  along  the 
Atlantic  Coast,  and  in  many  trucking  sections  of  the 
South,  hundreds  of  acres  are  covered  with  sash  or  pro- 
tecting cloth,  and  used  in  forcing  vegetables  for  market. 

Importance  of  vegetable  forcing. — The  value  of  frame 
and  greenhouse-grown  vegetables  in  the  United  States 
amounts  to  millions  of  dollars  annually.  The  importance 
of  the  industry  from  the  commercial  standpoint  can 
scarcely  be  overestimated.  There  are  other  considera- 
tions, too,  which  should  not  be  overlooked.  Among  them 
are :  (1)  Better  facilities  with  which  to  start  early  vege- 
table plants  for  outdoor  culture ;  probably  90  per  cent  of 
our  greenhouse  vegetable  growers  are  also  market  gar- 
deners or  truckers.  (2)  The  possibility  of  keeping  in 
touch  with  one's  patrons  between  the  summer  seasons. 
(3)  The  ability  to  give  employment  during  the  winter  to 
the  most  satisfactory  employees.  (4)  The  increased 
pleasures  of  rural  life  during  the  winter  by  creating 
summer  conditions  on  a  small  part  of  the  farm. 

Types  of  vegetable  forcing. — There  are  five  rather  dis- 
tinct types  of  vegetable  forcing,  namely :  (1)  By  the  use 
of  manure-heated  hotbeds.  This  is  the  oldest  type  used 
in  the  United  States,  and  it  is  still  practiced  to  some 
extent  by  commercial  growers.  Its  chief  value,  however, 
is  for  the  farmer  and  village  gardener  who  desire  a  con- 
tinuous supply  of  fresh  vegetables  for  their  own  tables. 

(2)  By  the  growing  of  crops  on  a  large  commercial 
scale  in  frames  heated  by  steam  or  hot  water,  or  merely 
covered  with  glass  or  protecting  cloth.     This  type  of 
forcing  is  especially  important   in   southern   gardening 
districts. 

(3)  By  the  growing  of  vegetables  for  the  home  table 
by  people  who  can  afford  to  operate  greenhouses  solely 


A   GENERAL   VIEW  5 

for  this  purpose.  This  phase  of  vegetable  forcing  will 
become  more  and  more  important  as  the  wealthier  classes 
become  acquainted  with  the  superiority  of  greenhouse 
products. 

(4)  By  erecting  small  greenhouses,  primarily  for  start- 
ing early  vegetables  for  outdoor  planting,  which  are  large 
enough  to  yield  a  profit  in  the  forcing  of  vegetables  when 
the  space  is  not  otherwise  in  demand. 

(5)  By  the  construction  of  very  large  ranges  for  the 
sole  purpose  of  growing  and  maturing  vegetables  out  of 
season.     The  owners  of  many  of  the  largest  establish- 
ments are  also  market  gardeners,  who  utilize  a  small  per- 
centage of  the  greenhouse  space  for  the  starting  of  early 
plants. 

Organization. — The  vegetable-forcing  interests  of  the 
United  States  are  fairly  well  organized.  In  1908  the 
Greenhouse  Vegetable  Growers'  and  Market  Gardeners' 
Association  of  America  was  organized  at  Cleveland,  Ohio. 
A  few  years  later  the  name  was  changed  to  the  Vegetable 
Growers'  Association  of  America.  While  the  society  has 
for  its  object  the  promotion  of  all  types  of  vegetable 
gardening,  the  forcing  interests  have  received  much 
attention  because  many  of  the  members  have  been  promi- 
nent growers  of  vegetables  under  glass.  This  organiza- 
tion is"  one  of  the  strongest  horticultural  societies  in 
America,  and  it  is  exerting  a  strong  influence  upon  the 
development  of  vegetable  forcing. 

The  widest  field  for  organization,  however,  is  in  the 
development  of  co-operative  associations.  These  have 
been  formed  in  many  of  the  most  important  forcing 
centers,  and  it  is  hoped  that  the  movement  will  continue 
until  every  district  is  organized. 

The  following  are  some  of  the  advantages  or  benefits  of 
co-operation :  (1)  Educational.  The  strongest  associa- 
tions hold  regular  meetings,  in  which  methods  are  dis- 
cussed and  the  entire  industry  considered.  (2)  One  of 


6  VEGETABLE  FORCING 

the  marked  advantages  is  in  the  selling  of  produce.  A 
shrewd  business  man  can  attend  to  all  sales.  To  obtain 
the  best  prices  he  must  be  constantly  informed  of  crop 
conditions  in  competing  sections,  and  he  must  have  a 
thorough  knowledge  of  the  problems  relating  to  distribu- 
tion. If  all  greenhouse  sections  were  properly  organized 
and  affiliated  with  a  general  organization,  market  slumps 
would  rarely  occur.  (3)  Supplies,  such  as  greenhouse- 
building  materials,  pipe,  tools  and  fertilizers,  may  be 
purchased  at  lower  cost  because  of  larger  orders. 
(4)  Each  community  might  work  to  advantage  through 
its  organization  in  the  production  of  well-bred  seed.  This 
would  be  especially  valuable  in  obtaining  greater  uni- 
formity of  the  products  offered  for  sale.  (5)  Organization 
promotes  uniformity  in  the  packages  used,  and  also  more 
thorough  and  skillful  grading  and  packing.  (6)  If  the 
produce  is  sold  through  a  general  manager,  the  grower  is 
relieved  of  the  worry,  trouble  and  responsibility  of  finding 
a  market,  and  is  thus  permitted  to  devote  all  his  energy 
to  production.  (7)  Fraternal  advantages.  Growers  are 
brought  closer  together  and  the  community  enjoys  a  more 
delightful  fellowship  than  is  possible  when  neighbors  are 
constantly  competing  with  one  another  in  business 
matters. 

Southern  competition  is  unquestionably  the  most 
serious  obstacle  to  the  development  of  vegetable  forcing 
in  the  North.  There  are  times  when  southern-grown 
lettuce,  cucumbers  and  tomatoes  are  rushed  to  the  great 
markets  in  such  enormous  quantities  that  northern  green- 
house growers  are  forced  to  sell  their  products  at  very 
low  prices.  These  periods  of  depression  occur  almost 
every  year  and  are  barriers  to  the  extension  of  the  forcing 
industry;  the  result  is  to  make  greenhouse  building  in 
the  various  sections  rather  spasmodic.  For  example, 
Boston,  in  1910,  built  no  houses  for  vegetable  forcing 
because  of  the  two  discouraging  previous  seasons,  when 


A  GENERAL  VIEW  7 

Florida  sent  immense  quantities  of  head  lettuce  to  Boston 
and  other  markets  of  the  Boston  growers.  Mishaps  in 
the  Florida  fields  since  1909  have  improved  market  condi- 
tions for  head  lettuce  in  the  East,  so  that  greenhouse 
building  about  Boston  was  a  few  years  later  more  active. 
The  western  growers  have  also  felt  the  keen  competition 
of  southern  gardeners ;  notwithstanding  this  -fact,  there 
has  been  a  very  large  increase  of  the  glass  area  in  most  of 
the  Middle  States  in  recent  years. 

The  superior  quality  of  greenhouse  vegetables  is  be- 
coming more  generally  recognized  every  year,  and  this  is 
the  factor  that  assures  the  successful  grower  of  at  least 
reasonable  profits.  The  southern  field-grown  vegetables 
sometimes  find  their  way  to  the  garbage  disposal  plants, 
while  the  better  products  of  the  greenhouses  are  sold, 
though  the  prices  may  be  very  low.  There  can  be  no 
discounting  the  fact  that  tomatoes,  fully  ripened  on  the 
plants  in  the  greenhouse,  are  far  superior  in  quality  to  the 
field-grown  specimens  picked  green  or  only  partially  ripe, 
and  held  for  days  in  transportation  and  by  a  long  line  of 
middlemen  before  arriving  at  the  consumer's  table. 
Similar  statements  might  be  made  regarding  other 
important  forcing  crops. 

Above  all,  it  behooves  the  greenhouse  grower  of  vege- 
tables to  bear  in  mind  that  high  quality  is  the  first  con- 
sideration if  he  is  to  make  a  financial  success  of  his 
enterprise,  and  no  effort  should  be  spared  which  will  con- 
tribute to  that  end.  The  choice  of  good  varieties,  seed 
selection,  proper  cultural  methods,  rigid  grading,  skillful 
packing  and  prompt  marketing,  all  count  for  high  quality, 
and  high  quality  counts  for  high  prices. 

Economic  production. — Greenhouse  growers  of  vege- 
tables usually  meet  with  competition  from  two  sources: 
First,  from  those  who  are  forcing  crops  under  artificial 
conditions;  and,  second,  from  cultivators  who  are  pro- 
ducing under  the  natural  conditions  of  the  field,  but  are 


8  VEGETABLE   FORCING 

handicapped  by  transportation  charges  and  other  diffi- 
culties. In  order  to  meet  the  competition  of  both  classes 
it  is  necessary  to  use  every  possible  means  to  maintain  a 
low  cost  of  production.  Greenhouse  growers  have  suc- 
ceeded remarkably  well  in  this  respect,  and  nothing  has 
contributed  so  much  to  the  advancement  and  extension  of 
the  industry. 

Various  factors  enter  into  this  problem,  the  following 
being  the  most  important :  (1)  Durable  and  substantial 
greenhouses  of  semi-iron  frame  construction  at  moderate 
cost.  (2)  The  elimination  of  benches,  concrete  beds  or 
other  fixtures,  which  increase  the  cost  of  construction  and 
maintenance,  interfere  with  tillage,  handling  of  manures 
and  the  general  management  of  the  house.  (3)  Improved 
systems  of  heating  and  ventilating.  (4)  Overhead  water- 
ing, which  reduces  the  cost  of  labor  for  this  operation  to 
a  minimum.  (5)  Better  facilities  for  harvesting  and 
marketing  greenhouse  crops.  (6)  Larger  greenhouses. 
The  cost  of  growing  100  pounds  of  lettuce  in  a  house 
covering  one-tenth  of  an  acre  is  necessarily  greater  than 
in  an  acre  or  a  five-acre  range.  (7)  Soil  sterilization  and 
better  sanitation  have  made  possible  the  use  of  the  same 
soil  indefinitely,  the  heavy  expense  of  making  frequent 
changes  of  the  soil  being  thus  eliminated.  (8)  Improved 
varieties  adapted  to  greenhouse  culture  have  done  much 
for  the  industry.  (9)  Proximity  to  market,  railroad,  and 
supplies  of  manure  and  coal.  (10)  A  trained  and  regular 
force  of  employees. 

Capital  required. — The  capital  required  to  engage  in  the 
vegetable-forcing  industry  depends  upon  conditions 
which  are  so  variable  that  it  is  difficult  to  give  estimates 
of  definite  value.  The  cost  of  a  good  semi-iron  form  of 
greenhouse  construction  for  an  acre  is  approximately 
$20,000,  although  such  houses  have  been  constructed  for 
several  thousand  dollars  less  than  that  sum ;  two  acres  of 
land  in  the  suburbs  of  a  good  market  would  probably  cost 


A    GENERAL   VIEW  9 

$1,000 ;  horse,  harness  and  wagon,  $300 ;  tools  and  equip- 
ment, $100;  manure,  $100;  operating  capital,  $800;  total, 
$22,300. 

Starting  on  a  smaller  scale,  say  10,000  square  feet  of 
house  space,  the  requirements  might  be  estimated  as 
follows:  Cost  of  house,  $5,000;  one  acre  of  land,  $500; 
horse,  harness  and  wagon,  $300;  tools  and  equipment, 
$75;  manure,  $25;  operating  capital,  $200;  total,  $3,100. 
Men  have  started  in  the  greenhouse  business  with  much 
less  capital,  especially  when  extra  land  was  available  for 
market  gardening.  It  is  not  desirable,  however,  for  any 
man  to  start  in  the  business  seriously  handicapped  by 
insufficient  capital. 

Profits. — Definite  statements  regarding  the  profits  of 
any  industry,  especially  along  horticultural  lines,  are 
usually  more  misleading  than  helpful.  Some  growers 
have  succeeded  in  paying  for  their  greenhouses  in  a  re- 
markably short  time,  from  the  profits  of  their  crops,  while 
others  have  absolutely  failed  to  realize  satisfactory 
profits.  In  this  respect  vegetable  forcing  is  not  unlike 
other  branches  of  olericulture — the  man  being  the  most 
important  factor  in  the  achievement  of  success.  The 
enterprise,  however,  certainly  compares  favorably  with 
other  lines  of  horticulture,  floriculture  not  excepted. 
Greenhouse  vegetable  growers,  as  a  class,  are  prosperous, 
and  the  rapid  expansion  of  their  ranges  speaks  well  for 
the  profits  of  the  industry. 

Location. — Most  men  now  engaged  in  this  industry  did 
not  deliberately  seek  the  best  conditions  for  the  growing 
of  crops  under  glass,  but  they  simply  concluded  that  the 
land  which  they  already  owned  was  sufficiently  well  lo- 
cated to  enable  them  to  realize  a  profit.  The  result  is  that 
some  establishments  are  advantageously  located,  while 
others  are  producing  under  the  most  unfavorable 
circumstances. 

When  it  is  possible  to  select  a  location  for  the  express 


10  VEGETABLE  FORCING 

purpose  of  vegetable  forcing,  the  following  considerations 
should  receive  attention  : 

(1)  Cost  of  fuel.    The  coal  bill  is  usually  the  heaviest 
item  of  expense,  although  the  labor  sometimes  costs  more. 
Growers  in  the  bituminous  regions  sometimes  obtain  coal 
at  the  mines  for  a  dollar  or  less  a  ton.    This  is  remarkably 
cheap  fuel  and  materially  lowers  the  cost  of  production 
when  compared  with  establishments  that  must  pay  from 
$3  to  $6  a  ton.     It  is  sometimes  claimed  that  our  great 
commercial  greenhouse  plants  should  be  located  at  the 
mines,  so  that  there  would  be  no  drayage  or  transporta- 
tion charges  of  any  kind,  so  far  as  fuel  is  concerned,  and 
this  view  of  the  problem  is  worth  considering.     It  is 
largely  a  question,  however,  whether  the  freight  charges 
on  a  ton  of  coal  from  the  mines  to  the  greenhouse,  the 
latter  located  presumably  at  the  market,  will  exceed  the 
express  charges  on  the  vegetables  produced  by  a  ton  of 
coal,  in  conveying  them  from  the  mines  to  the  market. 
In  most  instances,  however,  the  advantage  of  being  near 
a  good  local  market  much  more  than  offsets  the  disad- 
vantage of  transporting  coal  long  distances. 

(2)  Transportation  facilities.     Unless  located  within 
driving  distance  of  the  market,  the  greenhouse  should  be 
easily  accessible  by  railroad.    Many  of  the  largest  estab- 
lishments are  located  near  railroad  centers,  where  compe- 
tition secures  more  reasonable  freight  rates  and  several 
large  markets  are  easily  reached.     Electric  lines  often 
afford  cheap  and  satisfactory  transportation. 

(3)  A  large,  nearby  market  is  always  a  great  advan- 
tage.    Growers  who  sell  from  the  wagon  obtain  higher 
average  prices  than  those  who  must  make  consignments 
to  city  dealers. 

(4)  Although  many  successful  greenhouses  are  located 
on  heavy  soils,  the  sandy  types  are  preferred. 

(5)  There  must  be  an  ample  supply  of  water.     The 
evaporation  of  moisture  from  soil  in  a  greenhouse,  during 


A   GENERAL  VIEW  11 

the  spring  and  early  summer  months,  is  enormous.  It  is 
then  necessary  to  apply  water  every  day,  and  sometimes 
twice  a  day.  If  the  greenhouse  covers  an  acre  of  ground, 
26,963  gallons  of  water  will  be  required  to  equal  the 
quantity  that  would  be  applied  by  an  inch  of  rainfall. 

(6)  It  is  impossible  to  grow  greenhouse  crops  success- 
fully without  a  liberal  supply  of  manure.     Some  vege- 
table forcers  use  30  to  40  tons  annually  to  the  acre.    The 
supply  should  be  within  easy  reach,  and  the  cost  reason- 
able. 

(7)  Labor   should    be    easily    obtainable.      Vegetable 
forcing  is  an  all-year  proposition,  a  fact  which  simplifies 
the  problem  of  securing  and  keeping  the  necessary  help. 

(8)  A  clear  atmosphere,  free  from  the  smoke  of  fac- 
tories and  railroad  trains,  is  essential  to  success. 

Climatic  influences. — Although  the  grower  of  green- 
house vegetables  is  able  to  create  proper  conditions  for 
plant  growth,  yet  he  is  at  the  mercy  of  climatic  influences 
to  a  great  extent,  and  these  should  also  be  considered  in 
the  selection  of  a  location.  An  abundance  of  sunshine  is 
of  prime  importance  because  it  reduces  the  amount  of 
fuel  required,  accelerates  growth,  increases  yields, 
shortens  the  time  required  to  mature  a  crop,  and  de- 
creases the  ravages  of  disease.  Sunshine  is  particularly 
important  in  furnishing  favorable  conditions  for  polleniz- 
ing  the  flowers  of  fruit-bearing  plants,  such  as  the  tomato, 
pepper,  eggplant  and  cucumber. 

Southern  sections  have  a  greater  percentage  of  sunny 
days  during  the  winter  season  than  has  the  North. 
Furthermore,  fuel  consumption  depends  upon  the  dura- 
tion of  the  firing  period  and  the  severity  of  the  weather. 
Here,  the  South  again  has  the  advantage  over  the  North. 
Other  disadvantages,  however,  have  seemed  to  give 
northern  locations  the  preference  in  the  production  of 
greenhouse  vegetables  for  their  own  markets.  As  pre- 
viously stated,  the  frame  industry  in  the  South  is  very 


12  VEGETABLE  FORCING 

important,  owing  to  a  milder  climate,  and  there  is  now 
some  evidence  that  greenhouses  will  be  used  more  ex- 
tensively in  the  Middle  South  in  growing  products  for 
northern  markets. 

Relative  importance  of  forcing  crops. — Lettuce  un- 
doubtedly occupies  first  place  in  commercial  importance. 
It  is  grown  extensively  as  a  frame  crop,  and  is  the  leader 
in  nearly  all  large  forcing  establishments.  The  cucumber 
ranks  second  and  the  tomato  third,  although  the  tomato 
is  more  important  in  some  sections.  The  radish  ranks 
fourth  and  cauliflower  fifth.  Rhubarb,  asparagus,  beet, 
pepper  and  eggplant  are  grown  to  some  extent  and  the 
bean,  pea,  onion,  muskmelon,  asparagus,  witloof  chicory, 
carrot,  cress,  mints,  parsley,  spinach,  celery,  and  a  few 
other  vegetables  are  of  minor  importance. 

The  outlook. — The  outlook  for  vegetable  forcing  wras 
probably  never  better  than  at  present.  The  demand  for 
high-grade  vegetables  is  on  the  increase,  and  consumers 
want  them  the  year  round.  People  are  asking  for  the 
best,  and  the  best  grows  in  forcing  structures.  While 
prices  are  low  at  times,  they  average  just  as  high  as  they 
did  several  years  ago. 

Growers  are  better  able  to  meet  southern  competition. 
Modern  methods  of  greenhouse  construction  are  favor- 
able. Vegetable  forcing  appeals  to  many  people  because 
the  returns  are  so  prompt.  A  house  completed  the  middle 
of  October,  and  planted  at  once  with  strong,  frame-grown 
lettuce  plants,  will  yield  a  crop  for  Thanksgiving  and 
two  more  lettuce  crops  before  cucumbers  or  tomatoes  are 
planted  for  spring  and  summer  market.  With  successful 
management  and  good  prices,  the  cost  of  construction  is 
soon  covered,  but  a  certain  amount  of  conservatism  on 
the  part  of  greenhouse  vegetable  growers  is  highly  desir- 
able. It  is  better  not  to  make  large  extensions  in  the 
ranges  unless  the  results  assure  a  satisfactory  outlet  for 
the  increased  production. 


CHAPTER  II. 
GREENHOUSE  CONSTRUCTION  AND  HEATING 

The  purpose  of  this  chapter  is  to  discuss  the  principles  of  green- 
house construction  and  heating.  The  details  may  be  found  in 
special  books,  and  in  catalogs  of  manufacturers. 

Greenhouses  vs.  frames. — Frames  are  admirably 
adapted  to  vegetable  forcing  in  the  South,  but  for  the 
conditions  of  northern  latitudes,  greenhouses  are  vastly 
superior  for  most  purposes  to  frames.  Their  advantages 
are  numerous :  (1)  Heat  for  forcing  purposes  can  be 
generated  cheaper  by  the  burning  of  coal  than  by  the 
fermentation  of  manure.  (2)  All  cultural  conditions  may 
be  better  controlled  or  regulated  in  greenhouses  than  in 
frames.  (3)  The  labor  expenditure  on  a  given  area  is 
usually  much  less  in  greenhouses  than  in  frames. 
(4)  Shelter  during  inclement  weather  enables  the  em- 
ployer of  labor  to  follow  a  prearranged  plan,  and  to  utilize 
the  time  of  his  workmen  fully  and  economically.  (5)  In 
the  North  it  is  not  possible  to  grow  in  frames  at  mid- 
winter such  crops  as  tomatoes  and  cucumbers.  In  the 
vicinity  of  all  northern  cities  greenhouses  are  rapidly 
taking  the  place  of  hotbeds  and  coldframes,  not  only  for 
the  forcing  of  vegetables,  but  also  for  the  starting  of 
early  vegetable  plants.  Hotbeds  and  coldframes,  how- 
ever, have  an  important  place  in  the  vegetable  forcing 
industry,  and  their  uses  are  discussed  on  page  387. 

Site  and  position  of  house. — Any  protection  that  can 
be  afforded  by  trees,  hills,  buildings  or  special  wind- 
breaks, without  shading  the  house,  will  reduce  the  con- 
sumption of  fuel  and  aid  in  saving  the  structure  from 
damage  by  hard  windstorms.  It  is  advantageous  to  build 
on  level  land,  although  gentle  slopes  are  not  objectionable. 

13 


14 


VEGETABLE  FORCING 


The  position  of  the  house  with  reference  to  the  points 
of  the  compass  has  long  been  a  question  of  argument. 
Many  experienced  growers  positively  claim  that  it  makes 
no  difference  whether  the  house  runs  east  and  west  or 
north  and  south.  Houses  running  east  and  west  admit 
more  sunlight  during  the  short  days  of  the  winter,  while 
light  distribution  is  more  uniform  in  those  running  north 
and  south.  The  majority  of  vegetable  forcers,  especially 
growers  operating  three-quarter-span  houses,  probably 
prefer  buildings  running  east  and  west.  Many  growers 


Fig.  1. — A  modern  range  of  houses  at  Toledo,  Ohio. 

in  the  West  prefer  north  and  south  houses  because  of  the 
greater  comfort  in  working  in  them  in  hot  weather. 

Grading  the  land  generally  reduces  the  cost  of  con- 
struction, and  always  makes  the  work  in  the  daily  care  of 
crops  more  convenient.  Water  is  more  evenly  applied 
when  the  land  is  comparatively  level,  and  uniform  tem- 
peratures in  all  parts  of  the  range  are  more  easily 
maintained. 

Size  and  proportions. — Large  houses  have  many  ad- 
vantages. They  are  heated  more  economically,  and  the 
cost  of  operation  is  less  than  in  a  series  of  small  houses 
of  equal  area.  As  previously  stated,  it  is  not  uncommon 


GREENHOUSE    CONSTRUCTION    AND    HEATING  15 

to  find  single  houses  covering  an  acre  or  more  of  land, 
and  there  are  a  few  ranges  (Fig.  1)  that  cover  from  4 
to  10  acres  of  land. 

Houses  vary  greatly  in  width.  The  majority  of  the 
oldest  houses  range  from  9  to  12  feet  wide.  The  even, 
connected  ridge  and  furrow  type,  so  common  in  the  West, 
varies  from  15  to  18  feet  wide.  Numerous  commercial 
houses  are  from  20  to  24  feet  wide.  The  27-foot  standard 
house  of  the  West  has  many  advocates,  and  its  width  is 
considered  by  some  of  the  experienced  growers  the 
maximum  for  best  results. 

In  New  York,  New  Jersey  and  Pennsylvania  30  to  34- 
foot  houses  are  common,  while  Boston  inclines  toward 
the  40-foot  three-quarter  span.  (Fig.  2.)  Much  wider 


Fig.  2. — Typical  three-quarter-span  houses  of  the  Boston  district. 

houses  than  these  have  been  built  and  used  for  vegetable 
forcing.  There  is,  at  New  Castle,  Pa.,  a  hillside  three- 
quarter-span  house  (Fig.  3)  that  is  120  feet  wide;  and  a 
house  of  similar  form,  built  on  level  ground,  at  North 
Wales,  Pa.,  that  measures  172  feet  in  width.  These  are 
very  unusual  structures. 

Wide  houses  should  be  considered  with  special  refer- 
ence to  economy  of  heating.  Jn  actual  practice  the  air  in 
a  wide  house  with  greater  height  cannot  be  changed  as 
often  in  a  given  period  as  that  in  two  or  more  narrow 


16  VEGETABLE   FORCING 

houses  covering  the  same  area ;  furthermore,  there  is  not 
so  much  air  to  be  re-heated.  The  large  house,  therefore, 
requires  less  radiating  surface  and  less  fuel. 

The  length  of  the  house  is  not  of  great  consequence, 
although  unusual  length  should  be  avoided.  Most  of  the 
largest  houses  vary  from  200  to  600  feet  in  length.  Two 
hundred  feet  is  probably  the  maximum  which  can  be 
heated  satisfactorily  with  the  gravity  system  of  hot 
water,  but  with  forced  circulation  the  largest  ranges  may 
be  heated  economically  with  hot  water. 


Tig.  3. — Two-acre,    three-quarter-span    hillside    house    near   New    Castle,    Pa. 

Commercial  houses  are  built  much  higher  than  for- 
merly. For  many  years  it  was  the  belief  that  to  obtain 
the  best  results  the  glass  must  be  near  the  plants.  Suc- 
cessful growers,  however,  have  learned  that  better  crops 
may  be  grown  in  higher  houses.  The  distance  from 
ground  to  gutter  varies  from  5  to  9  feet  in  the  large 
modern  houses,  6^  feet  probably  being  the  most  popular 
height.  There  must  be  ample  room  for  the  training  of 
plants  and,  in  connected  ranges,  for  workmen  to  walk 
from  house  to  house  without  striking  their  heads  on  th~ 
gutters.  High  houses  make  it  possible  to  provide  free 
ventilation  without,  subjecting  the  plants  to  cold  drafts 


GREENHOUSE    CONSTRUCTION    AND    HEATING  17 

or  causing  great  fluctuations  in  temperature.  On  the 
other  hand,  great  height  increases  the  cost  of  construc- 
tion, and  renders  more  difficult  painting  and  repairing. 

Materials. — Efficiency  and  durability  should  be  the 
chief  aims  in  the  construction  of  greenhouses,  and  these 
can  only  be  attained  by  the  use  of  the  best  materials.  It 
is  false  economy  to  buy  cheap  lumber,  poor  pipe,  inferior 
glass  or  low-grade  materials  of  any  kind.  In  bench  con- 
struction, however,  pecky  or  worm-eaten  cypress,  because 
of  its  relatively  low  cost,  may  be  employed  to  advantage. 


Fig.  4. — Boiler  room  and  packing  house  of  a  ten-acre  range  near  Toledo,  Ohio. 

Arrangement  of  houses. — Houses  should  be  arranged 
with  special  reference  to  the  boiler  room  and  the  work- 
room. The  boilers  should  always  be  centrally  located. 
This  is  especially  important  if  the  gravity  system  of  hot 
water  heating  is  used.  A  centrally  located  packing  shed 
or  workroom  is  equally  important.  Fig.  4  shows  a  very 
satisfactory  arrangement.  The  trolley  car  is  receiving  a 
shipment  of  cucumbers  at  the  entrance  to  the  packing 
room.  Coal  is  brought  by  trolley  to  the  boilers  at  the 
other  end  of  this  building,  and  manure  to  the  large  ven- 
tilators along  the  sides  of  the  houses.  An  office  adjoins 
the  packing  room,  and  the  pumps  that  supply  the  water 


18  VEGETABLE  FORCING 

are  also  located  conveniently  to  the  boiler.  Wide  alleys 
(Fig.  5)  lead  from  various  parts  of  this  mammoth  range 
direct  to  the  packing  room.  When  the  products  are 
loaded  on  wagons  there  is  probably  no  better  arrange- 
ment than  a  low,  central  building  which  serves  as  a  drive- 
way, packing  shed,  office  and  boiler  room,  with  the  green- 
houses running  out  from  both  sides. 

The  greenhouses  should  not  be  shaded  more  than 
necessary  by  the  central  building.  As  a  general  rule,  very 
wide  houses  should  be  separate  because  they  shade  each 
other  more  than  do  narrow  ones.  In  the  East,  where 
wide  houses  are  most  used,  it  is  customary  to  leave  a 
space  of  12  to  16  feet  between  them.  The  fact  cannot  be 
disputed  that  wide,  separate  houses  admit  the  most  light, 
and  for  that  reason  they  are  best  adapted  to  the  winter 
culture  of  vegetables.  Separate  houses  are  well  suited  to 
regions  where  heavy  snowfalls  occur.  Nevertheless, 
because  they  are  more  expensive  to  construct  and  to  heat, 
they  do  not  meet  with  favor  in  many  sections,  especially 
in  the  West.  Separation  causes  inconvenience  in  the 
daily  care  of  the  crops.  Compact,  connected  ranges 
(Fig.  6)  are  entirely  satisfactory  under  most  conditions, 
especially  when  lettuce  is  the  main  winter  crop.  Many 
growers  prefer  the  even-span  type  of  construction  with 
connected  houses  30  to  40  feet  in  width.  (Fig.  7.) 

Forms  of  greenhouses. — There  are  three  general  forms 
or  types  of  greenhouses,  viz. :  (1)  Lean-to  or  half-span, 
(2)  even-span,  and  (3)  three-quarter  span.  Lean-to 
houses  (Fig.  8)  are  generally  built  against  the  south  side 
of  walls  or  buildings.  They  were  common  in  the  early 
days  of  vegetable  forcing.  They  are  fairly  satisfactory 
for  the  growing  of  a  few  vegetables  for  the  home  table, 
but  should  seldom  be  considered  for  the  growing  of  crops 
on  a  large  scale,  for  commercial  purposes.  They  are  in- 
expensive to  erect  and  economical  of  fuel,  but  their  limita- 
tions with  regard  to  light  and  sunshine  render  them 


20  VEGETABLE  FORCING 

unsuitable  for  vegetable  forcing,  especially  during  the 
short  days  of  winter. 

Even-span  houses  (Figs.  6  and  7)  are  in  common  use 
among  vegetable  growers.  In  this  type  of  house  the 
roof-bars  on  both  sides  of  the  ridge  are  of  equal  length, 
and  are  pitched  at  the  same  angle.  As  previously  stated, 
the  houses  may  or  may  not  be  connected  at  the  sides, 
although  the  tendency  is  to  connect  them.  Even-span 
houses  are  preferred  by  many  growers. 

Although  uneven-span  houses  are  popular  in  some  sec- 
tions, they  are  not  used  so  generally  in  vegetable  forcing 


Fig.  6. — Typical    even-span    range    of   narrow    units. 

as  are  even-span  structures.  In  this  form,  the  roof-bars 
on  one  side  of  the  ridge  are  longer  than  those  on  the 
other  side.  These  houses  usually  run  east  and  west ;  the 
southern  slopes,  being  longest,  admit  the  most  light 
during  the  short  days  of  winter.  Some  growers  who  pro- 
duce cucumbers  and  tomatoes  in  midwinter  claim  great 
superiority  for  the  uneven-span  house,  and  others  are 
doing  equally  well  in  even-span  houses  in  which  the  dis- 
tribution of  light  is  more  perfect.  The  length  of  the  two 
spans  varies  more  or  less. 

The  three-quarter  span  is  the  most  common.    It  is  used 
almost  exclusively  in  the  Boston  section  (Fig.  2),  where 


22  VEGETABLE  FORCING 

cucumbers  are  produced  to  a  considerable  extent  in  mid- 
winter. Fig.  3  shows  a  hillside  three-quarter-span  house 
at  New  Castle,  Pa.  The  house  is  120  feet  wide  and  600 
feet  long.  The  soil  for  a  distance  of  70  feet  from  the 
south  wall  rises  three  inches  to  the  foot,  while  the  50  feet 
of  ground  on  the  north  side  is  practically  level.  This 
mammoth  structure  has  been  highly  satisfactory  for  the 
growing  of  lettuce,  cucumbers  and  tomatoes. 

Two-third-span  houses  are  used  occasionally.  Near 
Chicago  and  in  other  western  sections  what  is  known  as 
the  "standard  house"  meets  with  favor.  The  houses  are 
27  feet  wide  and  they  run  east  and  west.  The  roof-bars 
on  the  north  side  are  16  feet  long,  and  on  the  south  side 
14  feet,  so  that  the  northern  slope  is  the  longer.  This  is 
a  radical  departure  from  the  three-quarter-span  houses  of 
the  East.  Perhaps  the  sole  purpose  of  the  14  and  16-foot 
slopes  is  to  avoid  shading  as  much  as  possible  in  these 
connected  houses,  for  the  ridge  runs  slightly  south  of  the 
center  of  the  house,  and  the  shadow  cast  by  it  during  the 
short  days  of  winter  falls  in  line  with  the  shadow  of  the 
north  gutter;  therefore,  only  one  shadow  is  cast  on  the 
plants  in  the  next  house  to  the  north. 

It  will  now  be  seen  that  the  form  of  a  house  is  largely 
a  matter  of  personal  preference,  and  from  the  results  of 
successful  growers  it  cannot  be  said  that  this  or  that  par- 
ticular type  is  best  adapted  to  vegetable  forcing.  Any 
form  of  modern  construction  will,  with  good  management, 
produce  satisfactory  crops. 

Wood  construction. — In  the  early  greenhouses  all  parts 
of  the  frame  were  made  of  wood,  but  in  recent  years  iron 
and  concrete  have  been  substituted,  wherever  possible, 
because  of  their  greater  durability.  If  for  any  reason  it 
seems  desirable  to  use  wood  throughout,  only  the  most 
durable  should  be  selected.  Cypress  is  now  employed 
almost  exclusively,  and  with  proper  care  it  will  last  for 
many  years. 


24 


VEGETABLE   FORCING 


Semi-iron  construction  (Fig.  10)  is  becoming  popular  in 
all  parts  of  the  country.  It  provides  for  concrete  walls, 
iron  posts  embedded  in  concrete,  iron  purlins  and  purlin 
supports,  iron  braces  and  sometimes  iron  eaves-plates. 
The  iron  may  be  in  the  form  of  pipe,  angle  irons,  or 
simply  flat  bars,  the  form  depending  upon  their  function 
and  the  cost  and  preference  of  the  builder.  With  the  best 
forms  of  semi-iron  construction,  decayed  wood  parts  are 
easily  removed  and  replaced  with  new  parts.  When  all 
exposed  parts  of  wood  and  iron  are  kept  properly  painted, 
the  house,  with  only  slight  repairs,  should  last  25  years, 
and  then  the  renewal  of  decayed  sash  bars  or  other  parts 


Fig.  9. — A  modern  steel-frame  house.     Note  large  door. 

should  prepare  it  for  many  more  years  of  service.  The 
moderate  cost  and  serviceability  of  semi-iron  construc- 
tion appeal  to  commercial  growers. 

Iron  construction  (Fig.  9)  is  the  strongest  and  most 
durable.  In  addition  to  the  iron  parts  used  for  semi-iron 
construction,  the  gutters,  wall  and  side  plates  are  metal, 
and  there  are  a  certain  number  of  iron  rafters  to  support 
the  roof,  so  that  interior  posts  are  unnecessary.  Iron  con- 
struction gives  the  house  greater  rigidity,  and  there  is 
less  shading  of  the  plants  because  of  the  absence  of  in- 
terior posts.  Full  iron  construction  costs  considerably 
more  than  semi-iron,  and  this  is  the  only  reason  why  it 
is  not  more  generally  employed. 


26 


VEGETABLE  FORCING 


Truss  construction. — In  recent  years  the  truss  form  of 
building  (Fig.  11)  has  received  considerable  attention 
from  greenhouse  men.  The  trussed  construction  makes 
it  possible  to  dispense  with  interior  posts,  except  in  very 
wide  houses,  and  comparatively  small  pipe  rafters  are 
used  instead  of  heavy,  flat,  iron  rafters  that  are  necessary 
in  full  iron-frame  houses.  The  sash  bars  are  also  smaller 
than  in  other  forms  of  houses,  so  that  every  detail  of  con- 
struction is  favorable  to  admitting  the  maximum  amount 
of  light  and  sunshine.  Theoretically,  this  is  the  ideal 


Fig.  11. — A   house   of  truss  construction. 


house,  and  it  is  highly  esteemed  by  many  vegetable 
forcers.  On  the  other  hand,  some  trussed  houses  have 
been  demolished  by  snow  and  storm,  and  growers  are 
naturally  rather  reluctant  about  building  houses  of  this 
type.  It  should  be  said,  however,  that  improvements 
have  been  made  which  add  to  the  strength  of  the  trussed 
houses,  and  it  is  possible  that  the  newer  houses  will  prove 
entirely  satisfactory.  Certainly  no  type  of  construction 
could  provide  better  conditions  for  the  culture  of  winter 
vegetables. 

Walls. — The  greenhouse  walls  should  be  durable  and 


GREENHOUSE   CONSTRUCTION    AND 'HEATING 


27 


give  adequate  support  to  the  superstructure.  They 
should  also  interfere  as  little  as  possible  with  the  admis- 
sion of  light  at  the  sides  and  ends  of  the  houses.  While 
wood,  stone  and  brick  are  sometimes  used  for  the  walls, 
concrete  is  now  almost  universally  employed  because  of 
its  economy  and  durability.  The  wall  must  have  a 
foundation  starting  below  the  frost  line — there  should  be 
no  uncertainty  about  this  matter.  For  large  houses  it 
should  be  not  less  than  a  foot  thick  at  the  bottom  and  8 
to  10  inches  at  the  top,  except  in  types  of  construction 


Fig.  12. — Semi-iron  construction,  showing  posts  and  purlin  supports  set  in  concrete. 

where  practically  no  weight  rests  directly  upon  the  wall. 
The  walls  in  some  of  the  largest  houses  are  only  4  or  5 
inches  thick,  and  this  may  be  ample  if  the  structures  are 
well  braced  and  supported  in  the  interior.  It  is  a  mistake 
to  build  the  concrete  walls  very  much  above  the  surface 
of  the  ground.  A  foot  is  ample  in  some  instances,  and  it 
is  doubtful  if  more  than  2*/2  feet  should  ever  be  allowed, 
because  the  extra  height  simply  adds  to  the  cost  of  con- 
struction, and  shades  the  plants  near  the  sides  and  ends 
of  the  house.  In  semi-iron  construction  (Fig.  12)  the  side 


28 


VEGETABLE   FORCING 


pipe  posts  are  set  in 
concrete  walls  and  the 
posts  supporting  the 
purlins  are  also  set  in 
concrete.  Glass  oc- 
cupies the  space  be- 
tween the  top  of  the 
wall  and  the  gutter  or 

Fig.   13. — A  common   form  of  wood  wall  sill.        side       olatC  Concrete 

walls  are  often  banked  with  soil  on  the  outside,  to  exclude 
cold.  When  this  is  not  desired  the  walls  may  be  given 
a  more  finished  appearance  by  applying  a  thin  coat  of 
Portland  cement. 

Frame. — All  wood  parts  of  the  frame,  including  wall 
plates,  eaves-plates,  headers,  sash  bars  and  ventilating 
sash,  are  prepared  at  the  factories,  so  that  the  work  of 
erection  can  readily  be  managed  by  a  local  carpenter  or 
anyone  who  uses  tools  efficiently.  The  same  may  be  said 
of  the  iron  and  truss  forms  of  construction,  although  they 
are  considered  more  difficult,  and  there  is  greater 
necessity  for  the  employment  of  skilled  mechanics. 

Wall  plate  or  sill. — The  size  and  form  of  wooden  wall 
sills  are  quite  variable.  Different  means  are  used  to 
secure  them  to  the  wall,  one  of  the  best  being  8-inch  bolts 
running  through  the  plates  at  frequent  intervals  and  em- 
bedded in  the  concrete.  The  lower  end  of  the  bolt  may 
be  bent  to  make  it  more  secure  in 
the  concrete,  and  a  burr  is  screwed 
on  the  upper  end  immediately 
above  the  plate.  Fig.  13  illus- 
trates a  common  form  of  wooden 
wall  sill. 

The  eaves  or  side  plates  of  sep- 
arate houses  vary  greatly  in  dif- 
ferent forms  of  construction.  The 
angle  iron  forms  of  eaves-plates 
(Fig.  14)  are  superior  to  all 


GREENHOUSE   CONSTRUCTION    AND   HEATING 


29 


wooden  plates  because 
of  their  smaller  size, 
durability  and  efficiency 
in  preventing  ice  from 
forming  along  the 

Fig.   15. — Wooden    gutter.  eaVCS 

Gutters  are  expensive,  difficult  to  keep  in  repair,  and 
being  wider  than  eaves-plates  they  cast  a  larger  shadow 
upon  the  plants  in  the  greenhouses.  Wooden  gutters, 
similar  to  the  one  shown  in  Fig.  15,  are  in  common  use. 
They  must  be  kept  well  painted  in  order  to  prevent  rapid 
decay.  Cast-iron  gutters  (Fig.  16)  are  more  satisfactory 
than  wooden  ones,  and  should  be  used  more  generally. 
They  are  made  in  great  variety,  but  drip  grooves  are 
essential  features. 

Sash  bars  for  the  roof,  sides  and  ends  vary  greatly  in 
size  and  to  some  extent  in  shape.  Fig.  17  shows  typical 
forms  of  roof  and  side  bars.  The  sash  bars  should  be 
large  enough  to  prevent  sagging  in  any  part  of  the  house, 
but  no  larger  than  necessary,  because  of  their  obstruction 
to  the  light.  Their  size  is  largely  dependent  upon  the 
strength  and  rigidity  of  the  supporting  structure  of  posts, 
purlins  and  braces.  The 
sizes  shown  in  the  illus- 
trations are  in  gen- 
eral use. 

Roof.  —  The  roof 
should  not  be  heavier 
than  necessary  to  se- 
cure proper  strength, 
and  it  should  be  built 
in  such  a  manner  that 
there  will  be  the  least 
obstruction  to  light  and 
sunshine.  The  pitch  of 
the  roof  should  receive 

rrmcirlfratirm  F'S-   l6- — Iron    8utter    with    roof   bars    con- 

lUUdiUCiailUIl.        nected.     Also  shows  connection  with  iron  post. 


30 


VEGETABLE   FORCING 


If  too  flat  there  will  be  danger  of  leakage,  and  snow  will 
be  likely  to  collect  on  the  glass. 

Light  will  thus  be  obstructed  and  the  increased  weight 
may  damage  the  roof.  In  deciding  upon  the  proper  pitch, 
not  only  must  snow  and  rain  be  taken  into  account,  but 
the  builder  must  bear  in  mind  that  the  rays  of  heat  and 
light  admitted  depend  very  largely  upon  the  inclination 
of  the  roof.  Modern  greenhouses  usually  have  a  pitch  of 
30  to  32  degrees.  A  pitch  of  30  degrees  reflects  8.4  per 
cent  of  the  sun's  rays,  and  a  pitch  of  35  degrees  reflects 
5.7  per  cent. 

Ventilators. — In  modern  greenhouse  management  the 
houses  are  in  use  the  year  around,  for  the  last  tomato  or 

cucumber  is  picked 
from  August  1  to 
August  15,  and  lettuce 
is  often  planted  early 
in  September;  the  in- 
tervening time  is  used 
in  cleaning  the  houses 
and  sterilizing  the  soil. 
For  the  good  of  the 
plants  and  the  health 
and  comfort  of  the 
workmen,  provision 
should  be  made  for  thorough  ventilation. 

In  houses  varying  from  12  to  18  feet  in  width  it  is 
customary  to  place  only  one  line  of  ventilators  at  the 
ridge,  and  this  should  not  open  toward  the  prevailing 
direction  of  the  wind.  In  wider  houses  there  should  be  a 
line  on  each  side  of  the  ridge  (Fig.  18),  and  it  is  usually 
desirable  also  to  have  ventilators  along  the  sides  as  shown 
in  this  illustration,  although  many  ranges  of  mammoth 
proportions  are  operated  without  side  ventilators.  The 
size  of  the  ventilating  sash  will  be  determined  by  the  size 
of  the  house,  but  they  should  be  amply  large. 


Fig.   17.—  (A)    A    typical    roof    bar 
(B)    Typical   end   bar. 


GREENHOUSE   CONSTRUCTION    AND    HEATING 


31 


The  ridge  ventilators  may  be  hinged  to  the  ridge  or  to 
the  header.  Some  growers  prefer  hinging  them  at  the 
ridge  (Fig.  1),  because  the  sash  practically  prevent  snow 
and  rain  from  entering  the  houses,  even  when  the  ven- 
tilators are  open  very  wide.  Other  growers  prefer  hing- 
ing at  the  header  (Fig.  18),  claiming  that  to  be  the  proper 
place  because  of  the  fact  that  the  condensed  water  on  the 
glass  of  the  ventilators  runs  off  instead  of  forming  ice  to 
interfere  with  the  closing  of  the  sash — a  frequent 
occurrence  when  the  sash  are  hinged  at  the  ridge. 

The  ventilating  sash  may  or  may  not  be  continuous. 
When  the  ends  of  the  sash  are  properly  fastened  to  each 


Fig.  18. — Semi-iron  house.     Note  large  door  and  ventilators  on  sides  and  end. 

other,  there  should  be  no  difficulty  in  operating  them.  A 
run  or  two  of  glass  between  the  sash  is  preferred  by 
many  growers,  but  continuous  ventilators  are  increasing 
in  popularity.  Sometimes  ventilators  are  placed  at  the 
ends  of  the  houses,  as  shown  in  Fig.  18. 

The  ventilating  machines  should  be  of  the  most  ap- 
proved type,  and  conveniently  located.  It  is  often  best  to 
have  them  near  the  doors  at  the  ends  of  the  houses. 
There  are  several  excellent  machines  on  the  market. 


32 


VEGETABLE  FORCING 


Fig.  19  shows  a  superior  type  that  is  used  in  many  houses. 

Posts,  purlins  and  braces. — Iron  pipe  is  now  used  al- 
most exclusively  for  posts  and  braces,  and  extensively  for 
purlins.  Advice  regarding  all  details,  such  as  size,  dis- 
tance between  the  posts  and  the  arrangement  of  them, 
should  be  obtained  from  the  manufacturers  furnishing  the 
supplies.  Fig.  12  shows  a  properly  supported  and 
well-braced  house.  The  posts  should  always  be  set  in 
cement,  to  prevent  the  settling  of  the 
house  and  the  lifting  of  the  roof  by  hard 
winds.  Angle  iron,  instead  of  pipe,  is 
sometimes  used  for  purlins. 

Doors. — The  doors  should  be  made  of 
cypress  and  amply  large  to  admit  carts 
and  wheelbarrows.  In  extensive  houses, 
at  least  one  door  should  be  large  enough 
to  admit  wagons,  horse  carts,  plows  and 
harrows.  (Fig.  20.)  Double  doors  are 
perhaps  the  most  convenient  and  the  most 
serviceable  for  excluding  cold. 

Glass. — What  is  universally  known  as 
"A  double  strength"  glass  is  practically 
the  only  kind  used  by  greenhouse 
builders.  Although  single  thickness  ad- 
mits the  maximum  amount  of  light,  it 
should  not  be  used  because  of  the  in- 
creased breakage  by  hail,  snow  and  freez- 
ing at  the  laps.  The  glass  should  be  clear, 
free  from  imperfection  and  of  uniform 
thickness. 

There  has  been  much  discussion  regarding  the  proper 
size  of  greenhouse  glass.  Originally  the  panes  were  very 
small,  10  x  12  inches  being  a  popular  size,  but  the  ten- 
dency is  to  use  larger  glass :  16  x  24  inches  is  by  far  the 


Fig.  19.— A  satis- 
factory machine  for 
operating  ventila- 
tors. 


GREENHOUSE    CONSTRUCTION    AND   HEATING  33 

most  popular  size.  Glass  of  this  size  is  generally  laid 
with  the  sash  bars  16  inches  apart,  although  a  small  per- 
centage of  vegetable  growers  lay  the  glass  with  the  sash 
bars  24  inches  apart.  Except  in  full  iron  construction,  it 
is  doubtful  whether  the  roof-bars  should  be  so  far  apart, 
because  of  the  increased  breakage  by  the  weight  of  snow, 
and  the  difficulty  of  making  and  maintaining  tight  joints 
at  the  laps.  There  is  probably  no  objection  to  the  bars 
being  20  inches  apart ;  this  distance  makes  it  possible  to 
use  20  x  24-inch  glass,  which  costs  only  a  trifle  more  than 
16  x  24-inch  glass. 


Fig.  20. — A   corridor   leading   to    the    packing    room    in    a    large    range. 

The  greenhouse  grower  has  been  quite  successful  in 
guarding  against  losses  caused  by  snow,  hard  winds  and 
very  cold  weather,  but  his  houses  are  at  the  mercy  of 
destructive  hailstorms.  To  protect  him  against  this  loss, 
hail  insurance  companies  have  been  organized.  One  of 
the  leading  companies  charges  8  cents  a  100  square  feet  of 
single-strength  glass  and  6  cents  for  double-strength.  It 
is  just  as  important  for  the  grower  to  protect  his  property 
from  losses  by  hail  as  from  those  by  fire. 


34 


VEGETABLE  FORCING 


Glazing. — Greenhouse  glass  is  usually  lapped  when 
laid,  although  it  is  sometimes  butted.  The  glazing  is 
performed  more  rapidly  when  the  glass  is  lapped,  and  it 
is  much  easier  to  replace  broken  panes.  There  is  also  less 
leakage  when  the  panes  are  lapped.  The  chief  objection 
to  lapping  is  that  more  or  less  dirt  and  soot  collect  be- 
tween the  laps.  Butted  glass  must  be  set  with  very  great 
care  in  order  to  make  the  joints  water-tight.  A  variety 
of  glazing  points  is  on  the  market. 

Previous  to  glazing,  all  wood  parts  of  the  greenhouse 
should  be  primed  with  one  coat  of  paint.  The  sash  bars 


Fig.  21. — Bench    with    pipe    frame    support. 


should  be  perfectly  dry  before  putty  is  applied,  and  the 
putty  should  be  of  the  best  grade  and  kept  soft  by  the  use 
of  linseed  oil.  It  may  be  applied  with  a  putty  bulb, 
machine  or  knife.  It  is  most  convenient  to  begin  at  the 
end  of  the  house  and  the  eaves,  and  then  to  work  up 
towards  the  ridge  until  the  first  row  is  completed,  next 
laying  the  second  row,  and  so  on  until  the  roof  is  finished. 
Sometimes  the  putty  is  applied  on  the  outside  of  the 


36  VEGETABLE  FORCING 

house,  but  this  is  generally  very  unsatisfactory.  It  is  far 
better  to  fill  the  rabbets  with  putty,  and  then  squeeze  out 
the  surplus  putty  by  forcing  the  panes  into  place. 

Glazing  points  are  used  to  fasten  the  glass,  and  when 
the  work  is  properly  done  the  joints  will  be  air  and  water- 
tight. A  matter  of  very  great  importance  is  often  neg- 
lected in  greenhouse  glazing.  Every  pane  of  glass  is 
curved.  The  panes  must  be  laid  with  the  curves  always 
up  or  always  down ;  otherwise  there  will  be  large  air 
spaces  between  the  laps.  When  the  sash  bars  are  pro- 
vided with  drip  grooves,  the  curve  should  be  up;  if  the 
grooves  are  lacking,  the  curve  should  be  down. 

Shading. — It  is  sometimes  necessary  to  shade  green- 
houses. A  cheap  and  rapid  method  of  providing  shade  is 
a  thin  whitewash  made  of  air-slaked  lime  and  applied  with 
a  spray  pump.  Such  a  wash  will  adhere  as  long  as  it  may 
be  needed,  and  there  will  be  no  difficulty  in  removing  it 
with  brush  and  water.  The  green  scum  which  often 
forms  on  old  greenhouses  may  be  easily  removed  with  a 
spraying  solution  made  by  dissolving  one  pound  of  oxalic 
acid  in  a  bucket  of  water.  A  crystalline  deposit  will  be 
formed  on  the  glass,  and  the  first  rain  will  wash  it  off. 
The  work  should  be  done  on  a  clear  day.  One  pound  of 
oxalic  acid  is  sufficient  for  3000  square  feet  of  glass. 

Painting. — Immediately  after  the  glass  is  laid,  the  house 
should  receive  two  additional  coats  of  paint,  and  there- 
after the  interior  and  exterior  should  be  painted  often 
enough  to  preserve  the  wood  parts.  Some  growers  paint 
the  outside  of  the  house  every  other  year,  although  most 
of  them  paint  at  much  longer  intervals.  There  is  some 
difference  of  opinion  regarding  the  value  of  subsequent 
painting  in  prolonging  the  life  of  a  greenhouse,  but  there 
is  no  question  about  the  value  of  paint  in  respect  to  the 
appearance  or  attractiveness  of  an  establishment.  It  is 
exceedingly  important  to  lead  properly  all  joints  when 


38  VEGETABLE   FORCING 

erecting  the  frame,  and  water  should  be  kept  out  of  the 
joints  by  the  frequent  application  of  thick  paint. 

Beds  and  benches. — Formerly  vegetables  were  grown 
almost  entirely  on  benches,  but  benches  are  seldom  seen 
in  the  large  modern  greenhouses  used  for  vegetable 
forcing.  It  is  argued  by  some  that  better  results  are 
obtained  with  benches,  and  there  are  doubtless  instances 
in  which  this  is  true,  but  the  disadvantages  so  far  over- 
balance the  advantages  that  benches  should  seldom  be 
given  serious  consideration,  except  for  midwinter  forcing 
of  warm  crops  and  for  sub-irrigation.  Among  the  disad- 
vantages of  benches  for  vegetable  forcing  may  be  men- 
tioned (1)  the  cost  of  construction ;  (2)  the  cost  of 
repairs ;  (3)  interference  with  the  operations  of  handling 
the  soil  and  manure,  and  of  spading,  plowing  and  harrow- 
ing, thus  increasing  the  cost  of  production  ;  (4)  the  soil  on 
the  benches  dries  out  much  quicker  than  the  solid  ground 
beds ;  (5)  more  skill  is  required  in  watering  the  soil  on 
benches,  unless  sub-irrigation  is  employed. 

In  the  modern  greenhouse  devoted  exclusively  to  vege- 
table forcing  there  is  no  necessity  either  for  benches  or  for 
sides  to  the  solid  beds.  The  whole  area  under  glass  is 
regarded  simply  as  one  unbroken  plat  which,  with  the 
exception  of  the  necessary  walks  and  alleys,  may  be  cul- 
tivated with  as  much  freedom  as  outside  gardens.  When 
benches  are  regarded  as  essential,  they  should  be  made  of 
durable  material.  Concrete  is  becoming  especially  popu- 
lar. The  construction  may  be  of  separate  blocks ;  or  the 
benches  may  be  made  with  a  \l/>  or  preferably  2-inch 
bottom  of  concrete  reinforced  with  poultry  netting,  and 
with  concrete  sides.  The  benches  may  be  supported  by 
iron  pipe  or  concrete  posts.  (Figs.  21  and  22.)  A  com- 
bination of  slate,  iron  and  concrete  is  often  used  in  bench 
construction.  Sometimes  water-tight  concrete  beds  are 
made,  so  that  sub-irrigation  can  be  practiced. 

Walks,   alleys  and  roadways. — Walks  in   commercial 


GREENHOUSE   CONSTRUCTION    AND   HEATING  39 

greenhouses  vary  from  12  to  24  inches  in  width.  Twenty 
inches  provides  sufficient  space  under  most  circum- 
stances. In  solid  plantings  of  lettuce  it  is  customary  to 
omit  two  rows,  or  sometimes  only  one,  while  in  cucumber 
and  tomato  plantations  the  walks  are  30  inches  or  more. 
Special  alleys  (Figs.  5,  23  and  24)  and  roadways  (Fig.  25) 
are  important  in  very  large  ranges. 

The  walks  in  some  of  the  best  houses  are  made  of  con- 
crete. These  are  especially  desirable  in  heavy  soils.  They 
are  inexpensive  and  simple  to  construct.  The  ground 
should  be  graded  as  level  as  possible  before  the  walks  are 
outlined.  Use  2  x  4-inch  pieces  for  the  sides.  Care  must 
be  exercised  to  get  the  sides  straight.  Tamp  the  soil  in- 
side the  2  x  4-inch  pieces  (the  scantling  may  be  laid  flat  if 
desired)  until  within  an  inch  of  the  top.  Stretch  a  piece 
of  poultry  netting  over  the  tamped  soil,  and  hold  it  in 
place  with  bent  pieces  of  old  wire  stuck  into  the  soil  and 
hooked  over  the  netting.  Rather  thin  concrete  is  used, 
and  the  top  leveled  and  smoothed  in  the  usual  manner. 
The  poultry  netting  reinforcement  greatly  increases  the 
strength  of  the  walk,  and  economizes  concrete.  The  net- 
ting should  be  permitted  to  bulge  here  and  there  over  the 
soil  so  that  the  concrete  will  settle  all  around  the  meshes. 
Where  freezing  does  not  occur,  as  in  the  greenhouse,  it 
is  unnecessary  to  use  ashes  under  the  concrete.  The  2x4 
pieces  of  lumber  are  removed  after  the  concrete  is 
properly  set. 

Steam  vs.  hot  water  heating. — Modern  greenhouses  are 
heated  either  by  steam  or  hot  water.  Hot  water  is  almost 
invariably  preferred  for  small  greenhouses  because  the 
boilers  may  be  left  for  a  longer  period  at  night  without 
attention.  About  nine-tenths  of  the  large  establishments 
are  heated  by  steam,  and  the  growers  claim  that  the  steam 
system  costs  less  to  install  and  to  operate,  and  that  it 
gives  them  better  control  of  temperatures.  But  some  of 
the  owners  of  very  large  ranges  of  recent  construction  are 


40  VEGETABLE  FORCING 

using  hot  water,  and  they  also  claim  economy  in  fuel 
consumption,  and  better  atmospheric  conditions  for  the 
growth  of  the  plants.  Some  growers  have  a  combination 
of  steam  and  hot  water.  They  use  the  steam  only  in 
extremely  cold  weather  and  for  sterilizing  the  soil,  and 
also  for  operating  the  pumps. 

The  differences  in  the  various  methods  of  steam  and  hot 
water  heating  are  so  great  that  the  two  general  systems 
can  scarcely  be  compared.  It  may  be  said,  however,  that 
there  is  an  increased  tendency  to  use  the  improved 
methods  of  hot  water  heating  in  very  large  ranges,  and 
that  they  are  unquestionably  more  economical  for  small 
houses.  The  greater  durability  of  pipes  constantly  filled 
with  water  is  a  strong  point  in  favor  of  the  hot  water 
system. 

Radiation  required. — The  radiation  required  to  heat  a 
house  properly  depends  upon  the  exposure  and  the  pro- 
tection of  the  building,  the  area  of  glass  exposed,  the 
temperature  requirements  of  the  crops  grown,  the 
severity  of  the  weather  and  the  system  of  heating. 

One  of  the  leading  manufacturers  of  greenhouse  boilers 
uses  the  following  data  for  finding  the  number  of  square 
feet  of  pipe  surface  required  to  heat  the  house  to  various 
temperatures  with  the  gravity  hot  water  system  when  the 
outside  temperature  is  zero :  For  60  degrees  to  65  degrees 
divide  square  feet  of  glass  and  equivalent  by  2.62 ;  for  55 
degrees  to  60  degrees  divide  by  3;  for  50  degrees  to  55 
degrees  divide  by  3.46 ;  for  45  degrees  to  50  degrees  divide 
by  4;  for  40  degrees  to  45  degrees  divide  by  4.67.  Six 
square  feet  of  wall  area  should  be  figured  as  the  equiva- 
lent of  one  square  foot  of  glass.  The  divisors  named  un- 
doubtedly provide  much  more  liberal  radiation  than  is 
common  in  most  greenhouses  which  are  devoted  to  vege- 
table forcing,  but  it  is  better  to  have  too  much  radiation 
than  not  enough.  Steam  and  the  pressure  systems  of  hot 
water  require  less  radiation.  So  many  factors  enter  into 


42  VEGETABLE  FORCING 

this  problem  that  a  greenhouse  heating  specialist  should 
be  consulted  before  a  decision  upon  any  given  amount  of 
radiation  is  made,  unless  the  matter  has  been  determined 
by  actual  experience  or  observation. 

Systems  of  hot  water  heating. — There  are  three  distinct 
forms  of  hot  water  heating,  viz.,  the  open  tank  gravity 
system,  the  pressure  system  and  the  forced  circulation 
system.  The  gravity  system  is  the  oldest  and  is  still  used 
quite  extensively.  It  provides  for  open  tanks  and  large 
pipes.  With  it  there  must  be  ample  radiation.  Although 
plants  thrive  with  this  system,  it  is  not  popular  with  large 
commercial  growers,-  because  of  the  excessive  cost  of 
installation,  nor  is  it  satisfactory  in  very  long  houses. 

The  pressure  system  secured  by  the  use  of  mercury  and 
sometimes  by  safety  valves  is  quite  popular  and  satis- 
factory when  properly  installed  and  operated.  Of  the 
three  methods  of  heating  by  hot  water,  the  forced  circula- 
tion system  is  the  most  satisfactory  for  large  greenhouses. 
In  this  system  the  velocity  of  the  circulation  is  increased 
by  means  of  propellers  or  pumps  operated  by  motors  or 
engines.  With  forced  circulation  the  mains  and  coils 
need  not  be  so  large  as  with  the  gravity  system,  so  that 
the  cost  of  installation  is  not  greatly  in  excess  of  steam. 
This  system  does  not  require  a  large  volume  of  water  in 
the  boiler  and  radiating  pipes,  so  that  the  temperature  of 
the  house  is  under  more  perfect  control  than  with  the 
gravity  system,  and  all  parts  of  the  house  are  heated 
uniformly,  a  condition  not  possible  in  large  houses  in 
which  the  gravity  system  is  installed. 

Systems  of  steam  heating. — There  are  three  systems  of 
steam  heating.  (1)  The  low-pressure,  steam-gravity  re- 
turn. With  this  system  the  pipes  are  laid  in  the  same 
general  positions  as  with  gravity  hot  water,  care  being 
taken  to  avoid  water  pockets. 

(2)  "Low-pressure  steam  with  steam-return  trap.  It  is 
often  impracticable  or  undesirable  to  excavate  boiler  pits 


GREENHOUSE    CONSTRUCTION    AND    HEATING  43 

or  cellars  which  are  necessary  for  the  gravity  system  of 
steam  or  hot  water;  but  by  means  of  a  trap  located  above 
the  boiler,  the  water  of  condensation  is  returned  to  the 
boiler  without  causing  any  trouble  in  the  radiating  lines. 
This  system  is  strongly  indorsed  by  many  who  are  using 
it  for  the  heating  of  large  establishments. 

(3)  High-pressure  steam.  While  this  system  is  some- 
times used  in  the  heating  of  greenhouses,  it  is  not  satis- 
factory because  of  the  intensity  of  the  heat.  Reducing 
valves  may  be  used  to  lower  the  temperature  so  that  the 
average  temperature  in  the  radiating  pipes  of  the  house 
will  be  considerably  less  than  in  the  boiler  or  mains.  In 
this  case  it  is  necessary  to  use  a  pump  to  return  the  water 
of  condensation  to  the  boiler.  The  pump  may  be  operated 
by  the  high-pressure  steam. 

Location  of  pipes. — The  pipes  should  be  located  where 
they  will  not  seriously  interfere  with  the  work  in  the 
houses;  nor  should  they  be  placed,  unless  unavoidable, 
where  they  will  cast  shadows  on  the  plants.  In  practi- 
cally all  vegetable-growing  establishments  most  of  the 
pipes  are  placed  along  the  walks,  with  just  enough  in  the 
central  part  of  the  houses  to  secure  the  proper  circulation 
of  air.  Sometimes  the  central  pipes  are  placed  near  the 
ground,  but  more  frequently  overhead,  and  supported  by 
the  same  iron  posts  which  support  the  roof.  In  the 
Boston  district  the  interior  pipes  are  often  3  or  4  feet 
above  the  beds.  In  narrow  houses  it  is  unnecessary  to 
have  any  central  pipe  lines,  but  in  houses  with  a  width  of 
20  feet  or  more  central  pipes  are  a  great  advantage. 

The  boiler. — Boilers  are  made  either  of  cast  iron  or 
wrought  iron.  Cast-iron  boilers  are  the  more  durable, 
because  they  do  not  rust  so  badly  and  there  are  no  flues 
to  be  burned  out  as  in  wrought-iron  boilers.  On  the  other 
hand,  fuel  consumption  is  not  so  economical  as  in 
wrought-iron  boilers,  in  which  the  waterways  are  thinner. 

A  great  variety  of  steam  and  hot  water  boilers  is  avail- 


44  VEGETABLE   FORCING 

able  for  the  heating  of  greenhouses,  but  space  will  not 
permit  a  discussion  of  the  merits  and  characteristics  of 
each.  A  few  general  factors,  however,  should  be  taken 
into  account  in  the  selection  of  a  boiler,  and  they  may 
be  enumerated  as  follows:  (1)  The  boiler  should  be 
amply  large.  It  is  uneconomical  in  every  respect  to  force 
a  boiler  which  is  too  small  for  the  required  radiation. 
(2)  The  boiler  should  secure  perfect  combustion  of  the 
fuel  used.  (3)  A  long  fire  travel  is  essential  to  the  great- 
est efficiency.  (4)  Thin  waterways  are  a  decided  advan- 
tage. (5)  Horizontal  fire  box  surfaces  are  superior  to 
perpendicular  tubes  or  flues.  (6)  The  boiler  should  be 
easily  cleaned.  (7)  There  should  be  at  least  two  boilers, 
even  for  small  houses,  so  that  in  case  of  accident  to  one, 
the  other  may  be  used. 

Thermostats  are  used  to  some  extent  among  green- 
house growers.  They  are  electrical  devices  for  the  auto- 
matic regulation  and  indication  of  temperatures.  An 
electric  circuit  connects  with  battery  cells  and  a  bell,  if 
the  thermostat  is  to  be  used  as  an  alarm.  Sufficient  ex- 
pansion or  contraction  of  a  substance,  such  as  rubber  or 
metal,  closes  the  circuit  and  causes  the  bell  to  ring  when 
the  temperature  has  reached  a  dangerous  point.  Thermo- 
stats are  sometimes  used  in  greenhouses  which  are  not 
large  enough  to  require  a  fireman  throughout  the  night. 
In  such  cases  they  may  connect  with  a  bell  in  the  bed- 
room of  the  fireman,  or,  if  preferred,  to  a  small  motor 
which  will  automatically  open  or  close  the  dampers  of 
the  boiler. 

Thermostats  in  large  commercial  houses  are  in  keeping 
with  the  "safety  first"  policy.  Why  take  chances  on 
the  damaging  or  perhaps  total  loss  of  a  crop,  when  a 
few  dollars  will  provide  a  sleepless  night  watchman  that 
will  sound  a  warning  the  very  moment  the  temperature 
in  the  greenhouse  has  dropped  to  a  dangerous  point? 

Furthermore,  the  night  fireman  and  the  foreman  are 


w/////.- 


46  VEGETABLE  FORCING 

likely  to  be  much  more  faithful  in  the  performance  of  their 
duties  if  they  know  that  a  bell  will  inform  the  proprietor 
that  the  temperature  is  not  being  properly  controlled. 

It  is  not  unusual  for  illness  or  accident  to  interfere  with 
the  work  of  the  night  men,  and  in  more  than  one  instance 
the  sudden  death  of  the  fireman  has  caused  serious 
damage  to  the  crops  if  not  their  total  loss. 


CHAPTER  III 
SOILS 

Selection. — The  utmost  care  should  be  exercised  in  the 
selection  of  soil  for  vegetable  forcing,  for  however  skillful 
the  grower  may  be,  he  cannot  expect  complete  success 
without  the  most  favorable  soil  conditions.  Unfor- 
tunately, we  possess  very  little  basic  information  about 
greenhouse  soils,  for  they  have  not  been  studied  to  any 
great  extent  by  scientific  investigators.  Our  knowledge 
of  them  and  their  management  has  been  deduced  mainly 
from  the  experiences  of  successful  commercial  growers. 

Greenhouse  soils  abnormal. — The  soils  in  most  of  the 
greenhouses  devoted  to  vegetable  forcing  and  to  flori- 
culture are  abnormal  in  structure,  color,  organic  content, 
and  probably  in  chemical  composition.  Even  the  texture 
is  often  modified  by  the  addition  of  sand  and  ashes.  So 
great  are  the  alterations  in  some  instances  that  the  soils 
would  not  be  recognized  as  belonging  to  any  particular 
classified  types.  The  greenhouse  grower  strives  to 
establish  the  best  and  most  perfect  soil  conditions,  and 
the  returns  usually  justify  the  expenditure  of  as  much 
time  and  money  as  may  be  required  to  accomplish  this. 
His  problem  of  soil  management  is  radically  different 
from  that  of  the  general  farmer,  who  may  gradually  im- 
prove his  land  from  year  to  year,  while  the  greenhouse 
grower  should  secure  the  maximum  production  within  a 
year  or  two.  The  glass  structure  over  an  acre  of  land 
represents  a  large  investment.  This  fact  and  the  cost  of 
fuel  and  other  operating  expenses  make  it  imperative  to 
spare  no  effort  in  providing  the  very  best  soil. 

Texture. — The  texture  of  a  soil  is  characterized  by  the 
proportion  of  the  different-sized  mineral  particles  which 

47 


48  VEGETABLE  FORCING 

it  contains.  Classification  is  based  upon  mechanical 
analyses,  excluding  stones,  gravel  and  fragments  of  rocks 
which  do  not  pass  through  a  2-millimeter  sieve. 

Classification  of  soil  material 

The  figures  in  the  following  classification,*  represent 
per  cent;  the  minus  sign  ( — )  less;  plus  sign  (+)  more; 
the  hyphen  (-)  when  used  between  two  numbers,  as  20-50, 
should  read  from  20  per  cent  to  50  per  cent. 

Soils  containing  — 20  silt  and  clay : 

Coarse  sand:     25-}-  fine  gravel  and  coarse  sand  and  less  than 

50  any  other  grade. 
Sand:     25+    fine  gravel,   coarse   and   medium   sand,   and  less 

than  50  fine  sand. 
Fine  sand :     50+   fine   sand,   or  — 25   fine  gravel,   coarse   and 

medium  sand. 

Very  fine  sand :    50+  very  fine  sand. 
Soils  containing  20-50  silt  and  clay : 

Sandy  loam :    25+  fine  gravel,  coarse  and  medium  sand. 

Fine  sandy  loam:     50+  sand,  or  — 25  fine  gravel,  coarse  and 

medium  sand. 
Sandy  clay:    —20  silt. 
Soils  containing  50+  silt  and  clay: 
Loam :  — 20  clay,  — 50  silt. 
Silt  loam :    —20  clay,  50+  silt. 
Clay  loam :    20-30  clay,  —50  silt. 
Silty  clay  loam :    20-30  clay,  50+  silt. 
Clay:    30+  clay. 

It  is  seen  from  the  foregoing  classification  that  soils 
vary  greatly  in  the  proportion  of  the  different-sized 
mineral  particles.  In  the  coarse  sand  the  particles  are  the 
largest ;  in  the  clay  they  are  the  smallest. 

The  proper  soil  texture  is  an  exceedingly  important 
matter  with  reference  to  the  production  of  crops  under 
glass.  The  heavier  types,  such  as  the  loams,  silt  loams 
and  clay  loams,  are  universally  regarded  as  pre-eminently 
adapted  to  the  culture  of  the  staple  farm  crops.  Like- 
wise, the  value  of  the  sandy  types  has  been  recognized  for 
trucking  and  market  gardening,  although  many  classes  of 

*  Bulletin  78,  Bureau  of  Soils,  United  States  Department  of  Agriculture. 


SOILS  49 

vegetables  are  grown  successfully  upon  the  heavier  types 
of  soils.  In  the  forcing  of  vegetables  sand,  and  pre- 
sumably fairly  coarse  sand,  is  more  important  than  in 
trucking  or  market  gardening.  The  air  spaces  between 
the  particles  are  much  larger  in  coarse-grained  soils  than 
in  the  fine  silts  and  clays,  and  for  that  reason  such  soils 
are  not  so  solid  and  compact.  As  explained  by  the  fol- 
lowing statements,  the  open,  porous  character  of  sandy 
soils  makes  them  peculiarly  well  adapted  to  the  culture 
of  greenhouse  vegetables. 

(1)  Tillage  is  less  difficult  and  less  expensive  than  in 
heavy  soils.    This  factor  is  important  in  general  farming, 
but  vastly  more  important  in  the  handling  of  greenhouse 
soils,  since  so  much  of  the  work,  must  be  done  by  hand. 
When  plows  and  harrows  can  be  used  under  glass,  texture 
from  the  tillage  standpoint  is  not  so  important. 

(2)  Sandy  soils  are  well  aerated,  and  this  condition 
accelerates  chemical  activity.     In  other  words,  oxidation 
is  more  rapid  in  sandy  soils,  fertilizers  act  more  quickly 
and   stable   manures   decompose   and   become   available 
sooner  than  in  heavy  soils. 

(3)  Sandy  soils  are  valued  for  trucking  and  market 
gardening  because  they  are  light  and  warm,  and  crops 
mature  earlier  in  them  than  in  heavy  soils.     The  same 
influence  exists  in  the  greenhouse,  though  to  a  less  extent, 
because  moisture  and  temperature  conditions  are  arti- 
ficially controlled.     In  greenhouse  management,  time  of 
maturity  is  determined  mainly  by  the  date  of  planting; 
nevertheless,  sandy  soils  are  favorable  to  rapid  growth 
and  quick  maturity. 

(4)  It  is  important  for  greenhouse  soils  to  dry  quickly 
on  top  after  watering,  because  an  excessive  amount  of 
moisture  at  the  surface  is  conducive  to  plant  diseases. 
This    is    especially    true    in    lettuce    culture.      Surface 
evaporation  is  most  rapid  in  the  coarse  sands  and  slowest 
in  the  fine  silts  and  clays. 


50  VEGETABLE   FORCING 

(5)  Greenhouse    soils    should    absorb    water    rapidly 
without  subsequent  baking,  and  the  sandy  soils  are  ideal 
from  this  standpoint.    Their  power  to  retain  water  is  not 
so  great  as  that  of  silt  or  clay,  but  this  is  unimportant  in 
the  greenhouse,  where  it  is  possible  to  water  at  any  time. 
A  somewhat  heavier  subsoil,  however,  with  its  greater 
power   to   hold   moisture,   is   an   advantage   because    it 
requires  less  frequent  applications  of  water. 

(6)  Interior  evaporation  is  more  rapid  in  sandy  soils, 
and  this  is  thought  to  be  of  considerable  consequence  in 
relation   to   oxidation   and   nitrification,   both   of   which 
processes  are  very  active  in  the  best  greenhouse  soils. 

(7)  Sandy  soils  do  not  bake  seriously.    This  is  a  great 
advantage  in  dispensing  with  frequent  cultivation.     In 
the  large  forcing  establishments  many  of  the  sandy  soils, 
which  contain  a  large  amount  of  organic  matter,  are  never 
stirred  or  cultivated  at  any  time  after  the  final  preparation 
for  planting. 

(8)  Sandy  soils  offer  no  resistance  to  root  penetration 
and  they  encourage  the  development  of  the  most  extensive 
root  system. 

(9)  The  root  crops,  such  as  radishes  and  beets,  are 
smoother  and  more  uniform  in  shape,  and  they  develop 
fewer  fibrous  roots  when  grown  in  sandy  soils. 

(10)  Walking  on  the  ground,  required  by  harvesting 
the  crops,  does  not  injure  the  physical  properties  of  sandy 
soils  as  is  often  the  case  in  heavy  soils. 

(11)  Seed  sowing  and  transplanting  are  facilitated  in 
sandy  soils. 

(12)  Apparently  it  is  less  difficult  to  maintain  satis- 
factory sanitary  conditions  in   sandy  soils.     There   are 
evidences  that  various  diseases  appear  earlier  in  heavy 
soils,  from  which  they  seem  more  difficult  to  eradicate  by 
any  method  of  soil  management  or  sterilization. 

(13)  Sandy  soils  are  easily  sterilized.    If  the  soil  must 
be  shoveled  over  and  over  again,  as  when  steam  is  used 


SOILS  51 

in  pipes,  the  sandy  soils  are  handled  with  the  greatest 
ease.  There  is  always  danger  of  injuring  the  physical 
properties  of  heavy  soils  when  either  steam  or  formalin  is 
used  for  sterilization. 

(14)  Sandy  soils  have  a  wider  adaptation  to  greenhouse 
vegetables  than  do  the  heavier  types. 

So  important  is  sand  in  greenhouse  soils  that  it  is  often 
transported  long  distances  and  mixed  with  the  heavier 
soils  that  must  be  used.  The  financial  returns  from 
greenhouse  crops  probably  justify  the  practice ;  and  yet  it 
is  better  to  select  soils,  if  possible,  which  make  this 
expenditure  unnecessary.  There  is  an  increased  tendency 
to  mix  muck  with  various  types  of  soils  to  be  used  for  the 
forcing  of  vegetables.  This  practice  deserves  considera- 
tion wherever  a  supply  of  muck  is  easily  available.  Both 
light  and  heavy  soils  seem  to  be  improved  by  its  addition. 

Although  special  emphasis  has  been  given  to  the  im- 
portance of  coarse-grained  soils,  there  are  numerous 
examples  of  success  on  heavy  types.  When  a  first-class 
market  is  easily  accessible,  no  one  should  hesitate  to 
engage  in  vegetable  forcing  simply  because  a  light  soil  is 
not  available. 

Structure. — This  term  applies  to  the  arrangement  of  the 
mineral  matter  of  the  soil.  In  some  instances,  as  in  fine 
silts,  the  particles  are  in  such  intimate  contact  that  the 
soils  are  very  compact;  they  form  a  mass  that  is  not 
easily  penetrated  by  roots.  This  condition  is  most  un- 
satisfactory to  aeration,  surface  evaporation,  tillage,  soil 
sterilization,  seed  sowing  and  transplanting.  Soils  of  un- 
favorable structure  for  vegetable  forcing  can  be  greatly 
modified  by  proper  cultural  methods.  Tillage  may  be  the 
means  of  breaking  up  the  soil  into  granular  masses,  and 
lime  may  cause  the  particles  to  flocculate,  while  the  fiber 
of  stable  manures  separates  the  soil  into  small  masses. 
It  is  important,  however,  to  avoid  if  possible  the  selection 
of  soils  of  compact  structure  for  the  forcing  of  vegetables. 


52  VEGETABLE  FORCING 

Color. — Black  soils  are  usually  more  fertile  than  light- 
colored  soils,  although  there  are  many  exceptions.  The 
color  of  the  soil  is  of  greater  importance  in  the  forcing  of 
vegetables  than  it  is  in  the  production  of  crops  in  the  open 
ground.  This  is  due  to  the  great  power  of  dark  soils  to 
absorb  the  heat  rays  of  the  sun,  thus  reducing  the  amount 
of  fuel  required  to  maintain  proper  temperatures.  Black 
soils  are  also  good  radiators ;  the  heat  absorbed  during  the 
day  radiates  throughout  the  night.  The  advantage  of 
heat  gained  in  this  way  is  particularly  noticeable  in  the 
management  of  coldframes.  How  much  of  a  factor  it  is  in 
the  heating  of  greenhouses  has  not  been  determined,  but 
it  must  be  of  considerable  importance,  especially  when  a 
large  proportion  of  the  ground  is  not  shaded  by  plants. 
The  absorption  of  heat  accelerates  chemical  activities  in 
the  soil  and  also  has  some  influence  upon  the  soil's 
physical  properties. 

Organic  content. — All  classes  of  cultivators  have  long 
recognized  the  value  of  a  liberal  quantity  of  soil  organ'c 
matter.  Of  the  various  factors  which  contribute  to  plant 
growth,  this,  with  the  exception  of  water,  is  unquestion- 
ably the  most  important.  The  organic  matter  furnishes 
plant  food;  secures  better  aeration;  promotes  chemical 
activities;  improves  physical  properties;  darkens  the 
color;  increases  the  water-holding  power;  supplies  the 
best  conditions  for  the  work  of  friendly  bacteria;  in- 
creases the  rapidity  of  water  absorption;  favors  root 
penetration;  and  reduces  the  cost  of  tillage  operations. 
No  class  of  soils,  except  the  mucks,  contains  such  large 
amounts  of  organic  matter  as  do  greenhouse  soils  which 
have  been  used  for  many  years  in  producing  vegetables 
for  commercial  purposes. 

Water  content. — Greenhouse  soils  are  generally  quite 
constant  in  moisture  content  because  water  is  applied 
whenever  needed.  See  page  149,  which  relates  to  watering. 

Chemical  composition. — As  previously  stated  in  this 


SOILS  53 

chapter,  chemical  changes  are  very  rapid  in  greenhouse 
soils,  and  with  the  perfect  cultural  conditions  that  are 
maintained  in  well-managed  houses  there  never  should  be 
any  deficiency  of  soluble  plant  food.  See  Chapter  IV  on 
Manures,  Fertilizers  and  Lime. 

Depth. — Greenhouse  soils  vary  in  depth  from  6  to  15 
inches,  and  even  greater  depth  may  be  found  in  some  of 
the  soils  used  in  the  Boston  district.  Very  deep  soils  hold 
more  water,  of  course,  than  do  those  of  medium  depth, 
and  this  is  probably  their  greatest  advantage.  Exceed- 
ingly heavy  crops  have  been  grown  in  soils  ranging  from 
6  to  8  inches  in  depth,  so  that  it  is  not  so  much  a  question 
of  depth  as  of  perfection  of  all  other  cultural  require- 
ments, for  well-prepared  shallow  soils  give  better  results 
than  poorly-prepared  deep  ones.  Although  very  deep 
soils  require  less  frequent  watering,  they  are  more  ex- 
pensive to  prepare  for  planting  because  of  the  necessity  of 
spading,  or  even  trenching  in  some  instances. 

Drainage. — It  is  sometimes  necessary  to  tile  drain 
greenhouse  soils,  although  the  necessity  for  drainage  is 
never  so  great  as  in  the  uncovered  open  field.  When  tiles 
must  be  used  they  should  also  be  available  for  steam 
sterilization,  and  they  may  be  used  for  sub-irrigation. 
See  pages  97,  155.  If  suitable  soils  are  selected  for  vege- 
table forcing  there  will  seldom  be  any  necessity  for 
artificial  drainage. 

Muck  soil. — Pure  muck  soil  is  not  adapted  to  the  forc- 
ing of  the  standard  greenhouse  vegetables,  except  head 
lettuce,  but  when  mixed  with  heavier  soils  the  organic 
content  has  an  ameliorating  influence.  A  vegetable 
grower  in  Pennsylvania  built  a  modern  house  covering 
two  acres  of  Dekalb  gravelly  loam,  and  then  hauled  muck 
several  hundred  yards  and  spread  it  to  a  depth  of  4  or  5 
inches  over  the  entire  area  of  the  greenhouse.  The  soil 
was  plowed  and  harrowed  until  the  muck  was  thoroughly 
incorporated.  The  splendid  crops  grown  in  that  house 


54  VEGETABLE  FORCING 

testify  to  the  merits  of  the  radically  modified  soil.  While 
many  tons  of  organic  matter  were  added  by  the  use  of 
muck,  annual  applications  of  stable  manure  have  also 
been  required  to  produce  maximum  crops. 

Boston  soils. — The  soils  of  the  Boston  greenhouse 
section  belong  to  the  Glacial  and  Loessial  province.  In- 
asmuch as  the  region  has  not  yet  been  surveyed,  the  soil 
types  cannot  be  designated.  The  following  is  a  me- 
chanical analysis  of  a  typical  soil  from  one  of  the  Boston 
greenhouses : 

Water-retaining  capacity 67.90 

Organic  matter  15.18 

Gravel 5.75 

Coarse  sand  8.12 

Medium  sand 7.07 

Fine  sand  12.06 

Very  fine  sand 34.01 

Silt 2.10 

Fine  silt 0.20 

Clay 3.82 

It  is  evident  that  sand  largely  predominates  and  that 
there  is  also  a  liberal  proportion  of  gravel.  The  large 
amount  of  organic  matter  is  due  to  the  frequent  applica- 
tions of  horse  manure.  The  soils  are  well  aerated,  absorb 
water  rapidly,  dry  quickly  on  the  surface  and  are  well 
adapted  to  forcing  cucumbers,  tomatoes  and  head  lettuce. 

Chester  fine  sandy  loam. — Three-tenths  per  cent,  or 
1,472  acres,  of  the  soils  of  Chester  county,  Pa.,  belong  to 
this  type.  A  mechanical  analysis*  of  a  typical  sample  of 
the  Chester  fine  sandy  loam  gave  the  following  results, 
expressed  in  percentages : 

Fine  gravel  2.1 

Coarse  sand  10.4 

Medium  sand 69 

Fine  sand 23.3 

Very  fine  sand 19.7 

Silt 26.8 

Clay _  10.8 


*  Soil  Survey  of  Chester  County,  Pennsylvania,  U.  S.  Bureau  of  Soils. 


SOILS  55 

This  is  probably  the  best  tomato  soil  in  Chester  county, 
but  because  of  its  location  and  other  general  reasons  it  is 
not  used  so  extensively  as  the  Chester  loam  in  forcing 
either  tomatoes  or  carnations.  The  following  table  shows 
a  mechanical  analysis  of  the  Chester  loam  : 

Fine  gravel 3.3 

Coarse  sand 7.5 

Medium  sand 3.3 

Fine  sand  8.9 

Very  fine  sand 9.3 

Silt    48.2 

Clay 19.8 

This  soil  contains  enough  sand  to  make  it  fairly  satis- 
factory for  tomatoes  and  cucumbers.  It  is  regarded  as  a 
good  soil  for  general  farm  crops  rather  than  for  special 
crops,  though  it  produces  probably  half  of  the  greenhouse 
tomatoes  sold  in  Philadelphia. 

Ashtabula  soils. — The  soils  of  the  Ashtabula  forcing 
district  belong  to  the  Glacial  Lake  and  River  Terrace 
group,  and  to  the  Dunkirk  series,  the  Dunkirk  sandy  loam 
being  the  best  of  the  series  for  vegetable  forcing.  This 
soil  is  from  6  to  10  inches  deep,  with  a  subsoil  of  medium 
or  fine  sand.  Both  the  soil  and  subsoil  contain  scattered 
pebbles,  which  are  not  objectionable  in  the  forcing  of 
vegetables.  The  following  is  a  mechanical  analysis  of  a 
sample  of  Dunkirk  sandy  loam  : 

Organic  matter  2.23 

Gravel 0.80 

Coarse  sand  3.44 

Medium  sand 3.90 

Fine  sand 42.70 

Very  fine  sand 26.14 

Silt _. 13.02 

Clay 9.80 

It  should  be  noted  that  the  sample  was  selected  out  of 
doors  and  not  in  the  greenhouse,  and  this  accounts  for 


56  VEGETABLE   FORCING 

the  very  small  percentage  of  organic  matter  as  compared 
with  the  Boston  greenhouse  soil.  The  Ashtabula  soils 
are  famous  for  their  production  of  lettuce  and  cucumbers, 
and  tomatoes  are  also  grown  to  a  considerable  extent  in 
this  soil. 

Cleveland  soils. — The  best  vegetable  forcing  soil  of  the 
Cleveland  district  is  known  as  the  Dunkirk  fine  sandy 
loam.  Although  not  quite  so  coarse  in  texture  as  the 
Dunkirk  sandy  loam  used  at  Ashtabula,  it  is  highly 
satisfactory  for  the  growing  of  lettuce  and  tomatoes. 
Cucumbers  are  also  grown  in  this  soil  to  some  extent.  A 
mechanical  analysis  shows  the  following  results : 

Fine  gravel 0.7 

Coarse  sand 2.7 

Medium  sand 3.7 

Fine  sand 39.5 

Very  fine  sand 32.4 

Silt 11.2 

Clay 9.2 

Toledo  soils. — The  typical  trucking  soils  of  the  Toledo 
district  belong  to  the  Miami  series.  The  Miami  sand  is 
best  adapted  to  vegetables.  It  is  variable  in  composition, 
but  contains,  according  to  mechanical  analysis  made  by 
the  U.  S.  Bureau  of  Soils : 

Gravel Less  than  one  per  cent 

Coarse  gravel  1.64  to    3.74 

Sand 7.08  to  24.74 

Fine  sand  37.66  to  51.34 

Very  fine  sand 5.50  to  33.54 

Silt    5.45  to  15.60 

Clay    2.54  to     3.59 

Lansdale  silt  loam. — Tomatoes  are  grown  quite  ex- 
tensively in  this  soil,  near  Lansdale,  Pa.  It  is  regarded 
as  a  good  soil  for  general  farm  crops.  The  drainage  is 
good  and  the  soil  does  not  puddle  very  easily.  The 
following  is  a  mechanical  analysis  of  the  soil : 


SOILS  57 

Fine  gravel  °-2 

Coarse  sand 1-6 

Medium  sand  1-1 

Fine   sand 4.5 

Very  fine  sand 5.1 

Silt 68.2 

Clay 19.1 

This  cannot  be  regarded  as  a  first-class  soil  for  vege- 
table forcing,  and  yet  it  does  not  seem  difficult  to  main- 
tain good  physical  properties  in  the  Lansdale  silt  loam. 

Norfolk  series. — The  various  types  of  sandy  soils  of  the 
Norfolk  series  are  used  extensively  in  vegetable  forcing, 
especially  in  the  growing  of  frame  crops.  They  are  warm 
and  well  drained,  and  respond  readily  to  the  use  of 
manures  and  fertilizers.  The  following  table  shows  the 
texture  of  a  sample  of  Norfolk  fine  sandy  loam : 

Gravel 1.34 

Coarse  sand  21.14 

Medium  sand 21.90 

Fine  sand 15.84 

Very  fine  sand 5.66 

Silt 26.69 

Clay 7.46 

Irondequoit  soils. — The  Dunkirk  soils  are  found  in  the 
Irondequoit  greenhouse  section.  A  mechanical  analysis 
of  soil  from  Irondequoit  is  not  available,  but  the  Dunkirk 
gravelly  sandy  loam  analyzes  as  follows : 

Fine  gravel  3.7 

Coarse  sand  7.4 

Medium  sand 6.4 

Fine  sand 14.9 

Very  fine  sand 20.5 

Silt 37.0 

Clay 9.8 

Soil  adaptation. — The  student  has  probably  concluded 
from  the  discussion  in  this  chapter  that  a  great  variety  of 
soil  types  are  adapted  to  vegetable  forcing,  or  at  least  that 
greenhouse  vegetables  are  grown  on  soils  that  have  a 


58  VEGETABLE  FORCING 

wide  range  in  texture  and  structure.  The  latter  state- 
ment undoubtedly  is  true,  for  examples  can  be  cited  of 
greenhouse  crops  having  been  grown  with  entire  success 
in  soils  which  in  their  unimproved  state  possessed  few  if 
any  of  the  characteristics  that  are  regarded  as  important 
by  greenhouse  growers.  Production,  however,  under 
adverse  soil  conditions  is  always  more  costly  and  more 
difficult.  As  previously  stated,  the  sandy  types  are  best 
adapted  to  all  of  the  vegetables  which  are  grown  in 
frames  or  greenhouses. 


CHAPTER  IV 
MANURES,  LIME  AND  FERTILIZERS 

Need  of  plant  food. — Greenhouse  vegetable  forcing  is 
the  most  intensive  type  of  agriculture.  The  plants  are  set 
very  close  together,  so  that  a  maximum  draft  is  made  on 
the  supply  of  available  plant  food.  One  crop  follows 
another  in  close  succession,  and  in  a  well-managed  house 
there  is  practically  no  loss  of  time  or  space  from  Sep- 
tember 1  to  August  15.  Continuous  heavy  cropping 
under  glass  requires  much  more  plant  food  than  any  line 
of  outdoor  cropping  that  can  be  followed  in  temperate 
regions. 

Again,  the  greenhouse  vegetable  grower  raises  products 
of  high  money  value,  and  the  cost  of  the  plant  food  re- 
quired for  maximum  crops  is  so  insignificant,  compared 
with  the  net  returns,  that  he  cannot  afford  to  take  chances 
by  not  supplying  sufficient  nourishment.  It  is  not  un- 
common to  see  greenhouses  which  are  properly  heated 
and  ventilated  filled  with  crops  that  are  small  and  inferior 
because  the  plants  have  not  been  properly  fed  and  per- 
haps watered.  There  must  be  perfect  cultural  conditions 
in  every  respect  in  order  to  realize  the  utmost  returns. 
No  greenhouse  soil  has  yet  been  found  which  does  not 
need  frequent  and  liberal  applications  of  plant  food. 

Value  of  manures. — Numerous  investigations  have 
shown  that  the  crop-producing  power  of  a  soil  is  more 
dependent  upon  its  physical  than  upon  its  chemical 
composition.  In  other  words,  if  a  soil  possesses  the  best 
physical  properties,  plant  foods  are  not  likely  to  be  want- 
ing to  any  considerable  extent.  The  probabilities  are 
that  this  conclusion  of  the  soil  specialists  does  not  apply 
so  much  to  the  artificial  conditions  of  the  greenhouse  as  it 

59 


60  VEGETABLE  FORCING 

docs  to  the  open  ground,  for  our  best  growers  have  found 
it  necessary  to  make  very  heavy  annual  applications  of 
plant  food,  notwithstanding  the  fact  that  their  soils, 
which  have  been  managed  skillfully  for  so  many  years, 
are  acknowledged  to  be  most  superior  in  their  physical 
properties. 

It  should  be  noted,  however,  that  in  greenhouse 
management  stable  manure  has  been  relied  upon  almost 
wholly  as  the  source  of  plant  food,  and  it  has  also  been 
the  means  of  creating  and  maintaining  physical  condi- 
tions which  are  regarded  ideal  for  greenhouse  cropping. 
The  action  of  the  manure  in  decomposing  also  has  a  sani- 
tary influence  on  the  soil,  and  the  presence  of  the  organic 
matter  is  essential  to  the  bacterial  life.  There  are  scores 
and  perhaps  hundreds  of  vegetable  growers  who  believe 
that  manure  properly  used  meets  all  the  requirements  of 
greenhouse  soils  and  of  greenhouse  crops.  It  has  been 
the  chief  source  of  organic  matter  as  well  as  of  plant  food. 

Rhode  Island  experiments. — Interesting  experiments 
with  fertilizers,  manure,  cut  hay  and  cut  straw  were  made 
at  the  Rhode  Island  station,  and  reported  in  Bulletins  107 
and  128  of  that  station.  The  greenhouse  bench  was 
divided  into  four  plots.  Horse  manure  was  applied  to 
No.  1  at  the  rate  of  75  tons  to  the  acre.  Thirteen  pounds 
of  cut  hay  or  cut  rye  straw  (1^-inch  lengths)  was  used 
on  No.  2  and  No.  3,  in  addition  to  various  chemicals 
which  constituted  a  complete  fertilizer.  No.  4  was  also 
treated  with  chemicals,  but  the  hay  or  straw  was  omitted. 
Radishes,  tomatoes,  cucumbers  and  carnations  were 
grown  in  the  series  of  experiments  which  were  conducted 
for  two  seasons.  The  decreasing  yields  of  plot  1,  as  each 
season  advanced,  compared  with  the  other  plots  indicated 
that  "possible  denitrification  and  the  loss  of  some  of  the 
nitrogen  in  a  gaseous  condition,  also  the  fact  that  suffi- 
cient time  had  now  elapsed  for  a  considerable  degree  of 
decomposition  of  the  cut  straw  to  occur,  which  may  have 


62  VEGETABLE  FORCING 

been  especially  beneficial  to  the  physical  conditioruof  the 
soil."  As  a  whole,  plot  5,  which  received  no  cut  hay  or 
straw  but  the  same  chemicals  as  No.  3,  did  not  produce  as 
high  yields  as  the  other  plots.  This  experiment  seems 
to  indicate  that  any  kind  of  organic  matter  of  proper  tex- 
ture improves  the  physical  properties  of  greenhouse  soils, 
but  growers  should  not  conclude  that  it  would  be  a  safe 
practice  to  abandon  the  use  of  stable  manure  and  sub- 
stitute chemicals  and  cut  hay  or  cut  straw,  although  it  is 
possible  that  this  could  actually  be  done.  The  straw  was 
used  at  the  rate  of  about  10  tons  to  the  acre. 

Horse  manure. — Of  the  various  stable  manures,  horse 
manure  is  used  the  most  extensively  in  the  forcing  of 
vegetables.  It  is  sometimes  purchased  at  the  livery 
stables  in  the  large  cities  for  50  cents  a  two-horse  load.  A 
dollar  a  ton  is  a  common  price  in  the  smaller  towns  and 
cities.  Horse  manure  is  drier  and  looser  in  texture  than 
cow  manure,  and  it  is  also  quicker  in  action  and  more 
convenient  to  fork,  especially  when  used  as  a  mulch  for 
tomatoes  and  cucumbers.  Fresh  horse  manure  contains 
an  average  of  0.59  per  cent  of  nitrogen,  0.26  per  cent  of 
phosphoric  acid  and  0.48  per  cent  of  potash.  See  page  423. 
for  the  value  of  horse  manure  from  mushroom  beds. 

Cow  manure  is  valued  by  some  greenhouse  vegetable 
growers.  It  is  slow  in  action,  and  the  fresh  manure  may 
be  applied  nearer  the  time  of  planting  than  is  desirable 
with  fresh  horse  manure.  Cattle  manure  of  fine  texture 
may  be  bought  from  city  stockyards.  Sometimes  it  is 
dried  and  pulverized,  and  then  shipped  in  bags.  This 
special  product  is  convenient  to  use,  but  the  high  cost 
prohibits  its  use  in  large  commercial  establishments. 
Fresh  cow  manure  contains  about  0.42  per  cent  of 
nitrogen,  0.29  per  cent  of  phosphoric  acid  and  0.44  per 
cent  of  potash. 

Sheep  manure  has  long  been  popular  for  use  in  flori- 
culture, and  it  also  finds  some  sale  among  greenhouse 


MANURES,    LIME   AND    FERTILIZERS  63 

growers.  It  is  commonly  known  as  a  hot  manure  and  it 
decomposes  very  rapidly  in  the  warm,  moist  soil  of  the 
greenhouse.  Sheep  manure  contains  about  0.76  per  cent 
of  nitrogen,  0.39  per  cent  of  phosphoric  acid  and  0.59  per 
cent  of  potash.  The  high  nitrogen  content  makes  it 
imperative  to  use  the  manure  with  caution,  in  order  to 
avoid  injury  to  the  plants.  It  is  especially  valuable  for 
lettuce.  The  fine  texture  of  the  manure  also  enhances  its 
value. 

Poultry  manure  is  not  often  used  in  greenhouses,  but  it 
possesses  special  merit  for  lettuce  on  account  of  the  large 
amount  of  nitrogen  which  it  contains.  Analyses  show 
that  hen  manure  contains  0.8  to  2  per  cent  of  nitrogen, 
0.5  to  2  per  cent  of  phosphoric  acid  and  0.8  to  0.9  per  cent 
of  potash.  Like  sheep  manure,  it  cannot  be  used  freely 
without  danger  of  injury  to  the  plants.  The  fine  texture 
of  chicken  manure,  when  properly  preserved,  increases  its 
value  for  mixing  with  greenhouse  soil. 

Rate  of  application. — There  are  no  rules  governing  the 
rate  of  applying  manures  to  soils  for  vegetable  forcing. 
The  factors  which  enter  into  this  problem  most  largely 
are,  first,  the  cost  of  the  manure  and,  second,  the  cost  of 
transporting  it  to  the  greenhouses  whether  by  teams, 
electric  power  or  steam  power.  Wherever  it  can  be 
delivered  at  low  cost  there  is  a  tendency  to  use  large 
amounts,  perhaps  excessive  amounts,  of  manure.  The 
annual  applications  range  from  about  25  to  60  tons  of 
horse  manure  to  the  acre,  35  perhaps  being  the  average. 
A  ton  of  manure  applied  every  year  to  1000  square  feet 
of  ground  should  be  ample  to  produce  good  crops. 

The  texture  of  the  soil,  however,  should  be  considered 
in  this  connection.  Heavy  soils  demand  larger  and 
probably  more  frequent  applications  than  light  soife,  for 
i  few  years  at  least,  until  there  is  a  marked  increase  in 
the  supply  of  organic  matter.  In  a  new  range  75  tons  of 
rotten  manure  to  the  acre  was  applied  to  the  Hagerstown 


64  VEGETABLE  FORCING 

clay  loam  (limestone  soil)  before  starting  the  fall  crop  of 
lettuce,  and  there  was  no  evidence  that  the  application 
was  too  heavy.  In  the  clay  and  silt  soils  it  is  practically 
impossible  to  use  too  much  rotten  manure,  and  it  is 
seldom  that  manuring  is  overdone  in  the  lighter  soils. 
The  soils  in  many  of  the  large  establishments,  where 
vegetables  have  been  forced  for  a  long  term  of  years, 
seem  to  be  too  loose  and  porous,  and  to  be  lacking  in 
body,  but  the  excellent  crops  which  are  harvested  at 
regular  intervals  do  not  indicate  any  fault  in  the  composi- 
tion or  character  of  the  soils.  When  rotten  manure  is  to 
be  applied  to  benches  or  solid  beds  in  small  greenhouses, 
two  or  three  pounds  may  be  used  to  each  square  foot  of 
space. 

Liquid  manure  is  often  used  to  advantage  in  small 
greenhouses.  It  is  easily  prepared  by  placing  about  a 
bushel  of  fresh  horse  manure  or  old,  unleached  cow 
manure  in  a  half  barrel  of  water.  The  contents  should  be 
stirred  occasionally  for  a  few  days.  Before  making  appli- 
cations, dilute  with  three  or  four  parts  of  water  to  one  of 
the  liquid.  It  may  be  used  for  all  of  the  greenhouse  vege- 
tables without  any  danger  of  injury.  In  small  green- 
houses it  is  customary  to  pour  a  cupful  around  each  plant 
which  may  be  in  need  of  nourishment.  The  plan  is  too 
slow  and  tedious  for  use  in  large  establishments,  where 
nitrate  of  soda  is  preferred,  if  special  feeding  is  regarded 
as  necessary.  The  more  economical  plan,  however,  is  to 
prepare  the  soil  with  sufficient  plant  food,  so  that  subse- 
quent applications  will  be  unnecessary,  except  for  the 
mulching  of  tomatoes  and  cucumbers.  In  some  of  the 
large  floral  establishments  liquid  manure  is  prepared  in 
large  tanks,  from  which  it  is  piped  to  the  various  houses 
and  applied  with  a  hose  and  nozzle. 

The  functions  of  lime. — The  use  of  lime  in  the  forcing 
of  vegetables  is  on  the  increase.  Apparently  it  is  just  as 
important — perhaps  even  more  important — in  greenhouse 


MANURES,    LIME    AND    FERTILIZERS  65 

management  than  in  out-of-door  cropping.  The  func- 
tions of  lime  arc  varied  and  may  be  enumerated  -as 
follows:  (1)  It  is  an  important  food  clement  of  plants, 
although  all  soils  probably  contain  sufficient  lime  to  meet 
the  needs  of  greenhouse  vegetable  crops,  so  that  it  is  not 
considered  a  normal  fertilizer,  such  as  nitrogen,  phos- 
phorus and  potassium.  (2)  It  maintains  a  neutral  or 
alkaline  soil  solution  which  is  essential  to  the  most  satis- 
factory growth  of  some  crops,  especially  the  clovers. 
(3)  It  is  favorable  to  the  micro-organisms  of  the  soil 
which  are  so  important  in  relation  to  the  supply  of  avail- 
able nitrogen.  (4)  It  helps  to  maintain  satisfactory  sani- 
tary soil  conditions;  that  is,  it  promotes  the  work  of 
friendly  bacteria  and  retards  the  action  of  injurious  forms, 
and  of  certain  disease  germs  which  are  harmful  to  forcing 
crops.  In  the  management  of  greenhouse  soils  it  prob- 
ably pays  to  use  lime  for  its  beneficial  sanitary  effects, 
were  there  no  other  considerations.  (5)  It  liberates  plant 
food,  including  both  of  the  important  mineral  constitu- 
ents— phosphoric  acid  and  potash — although  this  function 
may  not  be  of  great  consequence  in  heavily  manured 
greenhouse  soils.  (6)  It  is  destructive  to  toxic  substances 
in  the  soil,  and  this  function  may  be  of  great  importance 
in  greenhouse  management  where  there  is  little  oppor- 
tunity for  long-time  rotations.  (7)  It  aids  in  the  breaking 
down  of  insoluble  compounds  and  in  making  them  avail- 
able to  plants.  (8)  It  forms  a  base  for  fixing  and  retain- 
ing humus.  (9)  It  flocculates  the  finest  particles  of  silt 
and  clay  soils  into  granular  masses,  thus  materially  im- 
proving the  physical  structure  of  such  soils.  After  treat- 
ment with  lime,  these  soils  are  more  open  and  porous, 
better  aerated,  more  easily  penetrated  by  plant  roots; 
they  dry  quicker  at  the  surface  and  possess  better 
physical  properties  in  every  respect  for  the  forcing  of 
vegetables.  All  heavy  soils  used  in  vegetable  forcing 
should  receive  frequent  and  liberal  applications  of  lime. 


66  VEGETABLE  FORCING 

(10)  It  has  some  effect  in  binding  sandy  soils,  but  this 
function  is  of  no  practical  value  in  relation  to  greenhouse 
soils. 

The  yields  of  greenhouse  crops  are  often  materially 
increased  by  the  application  of  lime,  and  every  commer- 
cial grower  should  conduct  simple  experiments  to 
determine  its  full  value.  It  is  improbable  that  any  harm 
can  result  from  the  use  of  reasonable  amounts. 

Commercial  fertilizers. — As  previously  stated,  commer- 
cial fertilizers  are  not  used  extensively  by  the  market 
growers  of  vegetables  under  glass.  In  the  chapters  relat- 
ing to  the  various  classes  of  vegetables,  experiments  will 
be  cited  in  which  fertilizers  have  been  used  advan- 
tageously. There  is  a  strong  impression  among  growers, 
however,  that  little  if  anything  is  to  be  gained  by  the  use 
of  chemicals,  and  the  statement  "that  more  harm  than 
good  has  been  done  by  the  use  of  fertilizers  in  vegetable 
forcing"  is  very  likely  a  truthful  assertion. 

As  early  as  1892,  Prof.  W.  J.  Green  of  the  Ohio  station, 
after  conducting  some  careful  experiments,  reported  the 
following  in  Bulletin  43  of  that  station : 

"It  may  be  urged  that  no  results  could  reasonably  be  expected 
from  the  use  of  any  fertilizing  ingredient  upon  a  soil  already  well 
supplied  with  plant  food.  The  persistency  with  which  the  virtues 
of  nitrate  of  soda  for  garden  crops  have  been  urged  has  led  many 
to  believe  that  it  can  be  used  with  profit,  even  upon  soils  already 
full  of  fertility. 

"This  experiment  does  not  show  that  nitrate  of  soda,  or  any  other 
fertilizer,  cannot  be  used  to  advantage  in  any  case,  but  rather  that 
the  limitations  to  their  use  are  narrower  than  is  commonly  sup- 
posed. The  soil  used  in  this  experiment  was  a  clay  loam.  To  fit 
such  a  soil  for  use  in  the  greenhouse  the  best  method  is  to  compost 
it  with  stable  manure,  and  such  is  the  course  generally  followed  by 
gardeners.  The  case  would  be  different  with  a  sandy  soil,  as  the 
addition  of  stable  manure,  in  order  to  make  it  friable  and  to  prevent 
baking,  is  not  so  essential  as  with  clay.  Less  stable  manure  would 
be  needed  with  a  sandy  soil  than  with  clay,  and  the  deficiency  in 
plant  food  could  be  made  up  with  commercial  fertilizers,  and  no 
doubt  at  a  profit.  A  clay  soil  could  be  made  friable  by  the  addition 


MANURES,    LIME    AND    FERTILIZERS  67 

of  sand  or  coal  ashes,  and  the  deficiency  made  up  as  above  stated, 
but  the  feasibility  of  this  plan  has  not  been  tested. 

"The  problem,  however,  was  not  to  determine  to  what  extent 
stable  manure  may  be  displaced  by  commercial  fertilizers,  but  rather 
to  what  extent  the  latter  may  be  used  in  connection  with  an  abun- 
dance of  the  former.  We  have  taken  the  conditions  as  we  find  them 
in  most  gardens  and  greenhouses,  and  the  verdict  of  our  experi- 
ment is  that  under  such  circumstances,  and  with  the  crops  grown 
in  this  experiment,  there  is  likely  to  be  no  profit  arising  from  the 
use  of  the  commercial  fertilizers  named." 

In  the  same  connection,  Prof.  Green  writes:  "The 
growth  of  plants  upon  the  separate  plots  was  noted  from 
time  to  time,  and  weights  and  measures  taken  at  time  of 
harvesting.  No  effect  from  the  use  of  any  fertilizer  could 
be  detected;  the  plots  were  as  uniform  as  though  the 
same  treatment  had  been  given  to  all.  The  crops  grown 
were  lettuce,  radishes  and  tomatoes." 

Complete  fertilizers  were  used  in  larger  amounts  than 
is  customary  out  of  doors,  but  not  so  freely  as  to  injure 
the  plants.  It  is  probable,  though,  that  with  the  decreas- 
ing supply  of  city  stable  manure,  greenhouse  growers  and 
market  gardeners  will  be  forced  to  resort  more  largely  to 
the  use  of  commercial  fertilizers.  It  is  also  probable  that 
less  manure  and  the  skillful  use  of  fertilizers  would  give 
just  as  good  results  as  the  exclusive  use  of  large  amounts 
of  manure. 

Sources  of  nitrogen. — Some  nitrogenous  fertilizers  be- 
come available  much  more  quickly  than  others.  High 
solubility  is  desirable,  for  the  grower  can  then  adjust  the 
supplemental  applications  more  accurately  to  the  needs  of 
the  crop.  It  is  assumed  that  every  grower  is  using  at  least 
some  stable  manure,  and  the  practical  and  often  perplex- 
ing problem  is,  how  much  and  what  kind  of  fertilizer  is 
needed  to  produce  the  best  results. 

Of  the  mineral  materials  which  contain  nitrogen, 
nitrate  of  soda  is  used  the  most  generally,  and  no  doubt 
more  largely  as  a  source  of  nitrogen  than  any  other 


68  VEGETABLE  FORCING 

commercial  fertilizer.  It  contains  about  15  per  cent  of 
nitrogen.  The  salt  dissolves  quickly  in  the  moisture  of 
the  soil,  when  it  immediately  becomes  available  to  plants. 
This  is  usually  the  cheapest  form  of  nitrogen. 

Sulphate  of  ammonia,  which  is  formed  from  waste 
materials  produced  in  the  manufacture  of  illuminating 
gas,  is  used  sometimes  in  the  fertilizing  of  greenhouse 
crops.  It  is  more  concentrated  than  nitrate  of  soda,  since 
it  contains  about  20  per  cent  of  nitrogen.  Lime  should 
be  used  in  conjunction  with  large  applications  of 
sulphate  of  ammonia  in  order  to  prevent  unfavorable 
chemical  conditions  in  the  soil. 

Of  the  organic  fertilizers,  dried  blood  is  probably  the 
most  popular.  It  consists  of  blood  from  the  animals 
slaughtered  in  the  great  packing  houses,  and  is  prepared 
for  market  by  evaporating,  drying  and  grinding.  The 
best  grades  of  dried  blood  contain  from  12  to  15  per  cent 
of  nitrogen.  While  dried  blood  is  not  nearly  so  available 
as  nitrate  of  soda,  it  decomposes  very  rapidly  in  the 
warm,  moist  soils  of  the  greenhouse,  and  when  properly 
applied  produces  most  excellent  results. 

Different  grades  of  tankage  are  also  available  for 
greenhouse  crops.  They  vary  greatly  in  the  amount  of 
nitrogen  which  they  contain,  and  also  in  the  fineness  of 
the  particles.  Tankage  consists  of  all  sorts  of  miscel- 
laneous refuse  of  packing  houses. 

Other  forms  of  nitrogenous  fertilizers  are  used  occa- 
sionally in  the  greenhouse,  but  they  are  not  important, 
except  the  various  forms  of  animal  bone  which  contain 
some  nitrogen.  These  are  especially  popular  among 
florists.  The  bone  preparations  seldom  contain  more 
than  4  or  5  per  cent  of  nitrogen.  The  nitrogen  in  bone 
meals  becomes  available  very  slowly,  and  this  is  the 
most  serious  objection  to  their  use  for  greenhouse  crops. 
On  the  other  hand,  large  quantities  of  bone  meal  may  be 
used  with  perfect  safety,  and  this  knowledge  adds  greatly 


MANURES,    LIME   AND    FERTILIZERS  69 

to  its  popularity.  The  availability  of  bone  meal  depends 
primarily  upon  its  state  of  division,  the  finest  decom- 
posing most  rapidly. 

Sources  of  phosphoric  acid. — As  previously  stated, 
ground  bone  is  used  extensively  by  florists  and  to  some 
extent  by  vegetable  forcers.  The  phosphoric  acid  in 
bone  meal  ranges  from  20  to  30  per  cent.  There  are  two 
classes,  viz.,  raw  bone  and  steamed  bone.  Raw  bone 
meal  is  coarser  in  texture,  contains  the  natural  fat  and 
decomposes  slowly.  Steamed  bone  meal  has  had  the 
fatty  material  removed  by  treating  the  bones  with  steam 
under  high  pressure  before  they  are  ground.  The 
steamed  bone  meals  and  flours  are  of  fine  texture,  and 
for  this  reason  and  because  of  the  absence  of  fats  they 
decompose  and  become  available  much  more  quickly 
than  the  raw  bones. 

Acid  phosphate  may  also  be  used  in  greenhouse  soils. 
In  this  form,  from  14  to  17  per  cent  of  the  phosphoric 
acid  is  available.  Floats,  or  the  untreated  ground  rock, 
might  also  be  used  to  advantage  in  greenhouse  soils 
which  are  so  heavily  charged  with  organic  matter. 

Thomas  slag,  which  contains  from  15  to  20  per  cent  of 
phosphoric  acid,  should  prove  satisfactory  in  vegetable 
forcing. 

Sources  of  potash. — Of  the  various  forms  of  potash, 
muriate  of  potash  is  used  most  extensively  for  open 
ground  crops,  and  there  is  no  evidence  that  it  is  not  as 
satisfactory  as  other  potash  materials  for  greenhouse 
work.  It  contains  about  50  per  cent  of  actual  potash. 
Sulphate  of  potash,  another  product  of  the  German 
mines,  contains  about  the  same  percentage  of  potash  as 
does  muriate  of  potash,  though  the  purer  grades  carry 
larger  amounts.  Tobacco  stems  and  wood  ashes  are 
also  available  as  sources  of  potash. 


CHAPTER  V 
SOIL  PREPARATION 

Ideal  conditions  in  the  greenhouse  must  be  created,  for 
no  soil  in  its  natural  state  possesses  all  of  the  requisites 
for  the  successful  production  of  forcing  crops.  The 
vegetable  forcer  should  be  able  to  grasp  the  particular 
problems  relating  to  the  preparation  of  the  soil  to  be 
used.  Hard  and  fast  rules  cannot  be  laid  down,  because 
conditions  are  extremely  variable.  Different  soils 
demand  different  treatment.  But  whatever  the  soil,  it 
must  have  the  required  physical  properties  and  contain 
an  abundance  of  available  plant  food.  It  must  also  be  as 
free  as  possible  from  harmful  insects  and  plant  diseases. 
The  greatest  care  should  be  exercised  in  the  preparation 
of  soils  for  forcing  purposes. 

Changing  soils. — In  the  early  stages  of  the  greenhouse 
business  gardeners  and  writers  on  vegetable  forcing 
considered  it  necessary  to  change  the  greenhouse  soil 
every  year  or  two.  Renewal  was  regarded  necessary  in 
order  to  provide  a  soil  which  possessed  the  correct 
physical  and  chemical  properties.  It  was  found,  too,  that 
insect  pests  and  plant  diseases  became  troublesome 
unless  the  soil  was  changed  quite  frequently.  The 
custom  is  a  good  one  for  small  greenhouses  and  private 
places  where  it  is  not  practicable  to  employ  modern 
methods  of  soil  preparation.  There  are  hundreds  of 
private  and  small  commercial  houses  where  steam  is  not 
available  for  sterilizing  the  soil.  Under  such  circum- 
stances it  may  be  best  to  renew  the  soil  quite  frequently. 
On  the  other  hand,  it  is  highly  probable  that  summer 
mulching  with  manure  and  sterilizing  with  formalin 
would  be  just  as  satisfactory  in  most  instances  as  chang- 

70 


SOIL  PREPARATION 


71 


ing  the  soil.  Furthermore,  the  grower  must  not  lose 
sight  of  the  fact  that  a  properly  handled  greenhouse  soil 
improves  in  its  physical  properties  from  year  to  year. 
This  is  particularly  true  of  the  heavier  types. 

In  greenhouses  covering  thousands  of  square  feet  of 
land,  soil  renewal  is  quite  out  of  the  question  and  rarely 
practiced.  To  take  out  the  old  soil  and  bring  in  the  new 
is  an  exceedingly  expensive  operation,  the  cost  far  sur- 
passing that  of  sterilization.  The  expense  of  soil 
preparation  outside  of  the  greenhouse  should  also  be 
considered  before  one  decides  to  make  frequent  renewals. 


Fig.  27. — Manure    is    usually    placed    in    compost    piles    near    the    houses. 
(In    this    instance,    mushroom    houses.) 

Composting. — In  many  of  the  smaller  greenhouses 
there  will  always  be  more  or  less  necessity  for  the  chang- 
ing of  soils,  and  the  managers  should  have  a  thorough 
knowledge  of  the  principles  and  practice  of  composting. 

Horse  manure  is  almost  universally  employed  in  com- 
posting (Fig.  27),  although  cow  manure  is  often  used  for 
this  purpose  by  florists.  To  make  composting  effective, 
three  things  must  be  accomplished :  (1)  The  fiber  of  the 


72  VEGETABLE  FORCING 

manure  must  be  well  decayed  so  that  it  will  be  short  and 
fine  before  the  soil  is  used  for  forcing  purposes.  (2)  The 
fiber  must  be  thoroughly  mixed  with  or  incorporated 
throughout  the  mass  of  soil.  (3)  The  soil  must  be  thor- 
oughly saturated  with  the  liquid  of  the  manure.  To 
accomplish  these  results  it  is  necessary  to  start  compost- 
ing well  in  advance  of  the  time  when  the  soil  will  be 
wanted  for  use  in  the  greenhouse.  The  actual  length  of 
time  required  to  make  a  good  compost  depends  upon  the 
character  of  the  soil  as  well  as  upon  the  manure.  If  the 
soil  is  heavy  and  the  manure  fresh  and  coarse,  much 
more  time  will  be  needed  than  if  the  soil  is  light  and  the 
manure  old  and  of  fine  texture.  The  time  required  for 
composting  also  depends  upon  the  method  employed. 

One  of  the  oldest  and  most  satisfactory  methods  is  to 
stack  manure  and  sods  in  alternate  layers.  The  piles  are 
generally  4  or  5  feet  deep  and  large  enough  to  meet  the 
needs  of  the  house.  Thick,  heavy  clover  and  grass  sods 
are  preferable.  They  may  be  cut  with  spades  and  hoes, 
or  more  rapidly  with  a  plow  set  to  run  very  shallow,  and 
then  cut  across  the  thin  furrow  slices  with  a  spade  or  an 
old  axe.  The  sods  and  manure  are  hauled  and  stacked 
as  near  to  the  greenhouse  as  possible,  so  that  the  com- 
posted materials  may  be  placed  in  the  greenhouse  with- 
out further  hauling  or  unnecessary  handling.  The 
relative  thickness  of  the  alternate  layers  of  manure  and 
compost  should  be  determined  mainly  by  the  character 
of  the  soil  used.  More  manure  is  needed  for  the  heavier 
soils  than  for  the  lighter  types.  When  the  sods  are 
grown  in  silt  and  clay  soils,  the  layers  of  manure  and 
sods  should  be  of  about  equal  thickness,  and  they  may 
range  from  10  to  15  inches. 

In  sandy  soils  the  layers  of  manure  may  be  several 
inches  less  in  thickness  than  the  sods;  10  inches  of 
manure  and  14  inches  of  soil  give  excellent  results. 
Compost  piles  of  this  character  should  be  started  at  least 


SOIL  PREPARATION  73 

six  months  in  advance  of  the  time  when  the  soil  will  be 
needed,  and  in  the  heavier  soils  a  year  will  give  a  better 
compost.  After  the  material  is  well  decayed,  it  is  cus- 
tomary to  cut  down  the  pile  in  thin  slices  with  a  sharp 
hoe  or  spade,  thus  reducing  the  fiber  to  a  finer  state  of 
division.  Sand  may  be  added  to  the  compost  and  this  is  a 
great  advantage  in  the  heavier  soils.  One  part  of  sand 
may  be  used  to  four  parts  of  compost.  This  plan  of 
composting  has  been  popular  for  many  years  among 
florists,  and  so  far  as  results  are  concerned  no  method  is 
superior. 

It  is  not  always  possible  or  practicable,  however,  to  use 
the  method  of  composting  which  has  just  been  described. 
Excellent  results  may  be  had  by  simply  piling  together 
good  soil  and  short,  fresh  horse  manure  in  the  proportion 
of  about  one  part  of  manure  by  bulk  to  three  or  four 
parts  of  soil.  At  least  three  or  four  months  should  elapse 
before  the  compost  is  used,  and  the  pile  should  be  turned 
occasionally  to  obtain  a  finer  and  more  homogeneous 
mass.  If  it  is  desired  to  use  the  soil  immediately  after 
mixing,  old,  fine  unleached  manure  should  be  used  in- 
stead of  fresh  manures.  As  good  results,  however,  can- 
not be  expected  from  newly-mixed  composts. 

A  third  plan  of  composting  is  to  stack  sods  for  a  year 
or  two,  and  then  mix  one  part  of  the  decayed  sods  with 
one  part  of  good  soil  and  one  part  of  manure,  adding 
another  part  of  sand  if  that  seems  desirable. 

Manuring  in  the  field. — Because  of  the  large  amount  of 
hand  labor  involved  in  the  various  methods  of  compost- 
ing, other  methods  of  soil  preparation  have  come  into 
general  use  which  are  more  economical  of  labor,  and  pro- 
ductive of  highly  satisfactory  results.  One  of  the  most 
popular  methods,  especially  among  florists,  is  to  spread 
manure  on  the  field  and  to  give  it  such  tillage  as  may  be 
required.  Good  soil,  preferably  a  clover  sod,  should  be 
selected  for  this  purpose. 


74  VEGETABLE  FORCING 

As  early  in  the  spring  as  the  ground  is  dry  enough  to 
be  worked,  and  after  some  manure  has  been  applied,  use 
a  disk  or  cutaway  harrow  repeatedly  until  the  sod  and 
manure  are  thoroughly  cut  up.  Then  apply  as  much 
more  fresh  horse  or  cow  manure  as  can  be  turned  under 
with  a  two-horse  plow.  It  may  be  an  advantage  for  a 
boy  to  follow  the  plow  with  a  fork  to  draw  into  the 
furrow  the  manure  which  would  interfere  with  the  next 
furrow  slice.  By  proper  management  it  will  be  possible 
to  plow  under  40  tons  or  more  of  manure  to  the  acre. 
After  plowing,  disk  the  soil,  apply  lime  if  desired,  and 
harrow  again.  More  rotten  manure,  if  it  is  needed,  may 
be  added  at  any  time  during  the  summer.  It  may  be 
necessary  to  plow  the  land  two  or  three  times  during  the 
summer,  and  the  plot  should  be  harrowed  often  enough 
to  thoroughly  reduce  the  fiber.  In  the  stiffer  soils,  a 
spring-tooth  harrow  should  be  used  occasionally  instead 
of  a  disk  harrow.  By  September  the  soil  should  be  in 
prime  condition  for  use.  The  old  soil,  when  hauled  back 
to  the  field  from  the  greenhouse,  furnishes  ideal  condi- 
tions for  market  garden  crops.  But  whatever  may  be 
said  regarding  the  merits  of  this  method  of  soil  prepara- 
tion, it  is  too  expensive  to  receive  the  serious  considera- 
tion of  extensive  commercial  growers,  although  far  more 
economical  than  any  of  the  usual  methods  of  hand 
composting. 

Green  manuring. — It  is  often  an  advantage  to  use  green 
manures  in  conjunction  with  field  applications  of  stable 
manures.  This  practice  will  be  found  of  special  value  in 
naturally  poor  soil  and  when  liberal  quantities  of  stable 
manure  are  inaccessible  or  very  expensive.  This  process 
of  increasing  the  supply  of  humus  may  be  begun  in  the 
fall  by  sowing  rye  at  the  rate  of  three  bushels  of  seed  to 
the  acre.  When  the  rye  is  about  a  foot  high  the  follow- 
ing spring  it  may  be  plowed  down  and  followed  with 
oats  and  Canada  field  peas,  or  with  cowpeas  or  soy  beans. 


SOIL   PREPARATION  75 

Michigan  growers  sow  rye  and  vetch  together  when 
the  seeding  can  be  done  fairly  early  in  the  fall. 

It  is  always  important  to  use  liberal  amounts  of  seed. 
Crimson  or  medium  red  clover  may  be  sown  in  August. 
At  each  plowing,  manure,  fertilizer  and  lime  may  be 
applied  in  such  amounts  as  seem  desirable.  Ultimately, 
the  sods  may  be  cut  for  composting,  or  the  soil  prepared 
for  the  greenhouse  as  described  on  page  72,  except  that 
less  manure  may  be  required.  Green  manures  have  also 
been  grown  inside  of  the  greenhouse,  but  the  interval 
between  the  harvesting  of  the  spring  crop  and  the  plant- 
ing of  the  fall  crop  is  too  brief  for  the  development  of 
much  organic  matter,  although  such  cropping  may  have 
a  sanitary  effect  upon  the  soil  and  also  improve  its 
physical  and  chemical  composition. 

Manuring  in  the  greenhouse. — It  is  the  almost  uni- 
versal practice  in  the  large  vegetable-forcing  establish- 
ments to  apply  the  manure  to  the  soil  in  the  greenhouses 
where  the  crops  are  to  be  grown.  It  is  not  difficult  to 
understand  why  this  is  the  favorite  practice.  There  is  no 
question  that  it  is  the  most  economical  from  the  labor- 
saving  standpoint,  for  in  many  of  the  best-managed 
places  the  manure  is  transported  from  the  car  or  compost 
heap  in  manure  spreaders,  with  which  it  is  applied  in  the 
greenhouse,  or  by  wagons  or  carts  and  spread  with  a 
fork.  There  is  no  reason  why  manure  spreaders  should 
not  be  used  for  this  purpose,  although  carts  are  more 
convenient  to  handle,  especially  in  houses  containing 
pipe  posts  or  roof  supports.  In  the  smaller  houses  it  is 
customary  to  transport  the  manure  into  the  houses  by 
means  of  wheelbarrows  or  hand  carts. 

The  manure  must  be  well  decayed  when  applied  direct 
to  the  soil  of  the  greenhouse  (unless  used  for  a  mulch), 
and  this  requires  composting  by  the  same  method  that 
is  so  common  among  market  gardeners.  That  is,  the 
manure  is  hauled  from  the  cars  and  stacked  firmly  in 


76  VEGETABLE  FORCING 

large,  flat  piles  4  or  5  feet  deep  and  with  perpendicular 
sides.  If  the  sides  are  built  up  straight,  there  will  be 
practically  no  leaching.  Water  is  applied  to  the  manure 
as  often  as  is  necessary  to  prevent  fire  fanging.  There 
can  be  no  leaching  in  the  interior  of  the  pile,  because  no 
rainfall  is  ever  heavy  enough  to  percolate  through  4  feet 
of  manure.  The  piles  should  be  turned  once  or  twice 
during  the  process  of  decay  to  assist  decomposition  and 
to  secure  a  product  of  finer  texture.  Railroad  sidings 
have  been  constructed  at  some  of  the  largest  establish- 
ments so  that  the  manure  may  be  thrown  on  the  compost 
piles  without  the  expense  of  hauling  on  wagons.  In 
other  instances  partly  decayed  manure  is  thrown  from 
the  cars  through  side  openings  of  the  greenhouse. 

Practically  all  growers  apply  the  manure  in  August  or 
September  before  the  work  of  sterilization  begins.  A 
very  successful  grower  at  Erie,  Pa.,  has  been  spreading 
short,  fresh  horse  manure  immediately  after  the  harvest 
of  tomatoes  and  cucumbers,  and  this  is  usually  from 
August  1  to  15.  The  soil  is  then  plowed,  limed,  harrowed 
and  watered.  Repeated  tillage  and  watering  during  the 
summer  seem  to  have  a  most  beneficial  effect  by  destroy- 
ing weeds  and  disease  germs,  and  these  operations  leave 
the  soil  in  excellent  physical  and  chemical  condition  for 
the  fall  and  winter  crops.  With  this  plan  of  soil  manipu- 
lation diseases  did  not  appear  for  many  years,  although 
steam  sterilization  is  now  practiced  in  these  houses,  but 
more  as  a  matter  of  insurance  against  loss  than  from  any 
knowledge  of  serious  infection  by  disease. 

Drying  greenhouse  soils. — In  hundreds  of  small  green- 
houses the  soil  is  permitted  to  become  very  dry  during 
the  summer  months  when  the  houses  are  not  in  use. 
The  desiccation  is  particularly  rapid  and  complete  when 
the  soil  is  on  raised  benches.  A  house  temperature  of  100 
degrees  or  more  is  an  almost  daily  occurrence,  and  under 
such  conditions  only  a  few  days  are  required  for  the  soil 


SOIL  PREPARATION  77 

to  become  very  dry.  In  general  farming,  drought  is 
thought  by  some  to  have  a  beneficial  effect  upon  the  soil, 
or  at  least  upon  the  following  crop,  but  it  is  possible  that 
this  is  due  largely  to  the  absence  of  leaching  and  the 
small  draft  upon  the  food  supply  of  the  soil  when  there 
is  a  marked  deficiency  in  the  supply  of  capillary  water. 
Though  drying  may  be  an  advantage  to  soils  out  of 
doors,  there  is  evidence  that  it  is  a  great  disadvantage  in 
the  management  of  greenhouse  soils,  except  for  the 
destruction  of  nematode  worms. 

Stone,  of  the  Massachusetts  station,  made  the  follow- 
ing report  in  1902 :  "The  practice  of  desiccation  or  dry- 
ing greenhouse  soil  by  the  aid  of  the  heat  of  the  summer 
sun  has  been  in  vogue  with  us  for  some  time,  for  the 
purpose  of  observing  what  effect  such  treatment  would 
have  on  certain  organisms.  We  have  already  shown  that 
the  sclerotina  or  the  drop  fungus  when  dried  is  greatly 
accelerated  in  its  activity,  which  increases  to  a  great 
extent  the  amount  of  infection  in  the  succeeding  crop  of 
lettuce." 

In  this  connection  Stone  further  reported  as  follows  in 
Bulletin  69  of  the  Hatch  station :  "In  this  test  the  house 
was  closed  during  the  greater  part  of  August,  September 
and  October,  at  which  time  the  soil  was  subjected  to  the 
intense  rays  of  the  sun,  which  heated  the  soil  up  to  a 
temperature  of  123  degrees,  and  the  air  thermometer 
registered  140  degrees.  As  the  top  layer  of  the  soil  be- 
came dry  a  lower  layer  to  the  depth  of  a  foot  was  forked 
over  two  or  three  times,  so  that  practically  the  whole 
amount  of  soil  became  desiccated.  The  results  of  drying 
out  the  soil  in  one  bed  containing  308  plants  was  that  235, 
or  76  per  cent,  were  subject  to  drop,  and  66,  or  21  per 
cent,  to  Rhizoctonia.  The  number  of  plants  which  suc- 
cumbed to  the  two  diseases  was  301  out  of  a  total  of  308, 
or  97  per  cent.  The  other  half  of  the  house,  containing 


78  VEGETABLE   FORCING 

264  plants,  was  treated  similarly,  with  about  the  same 
results." 

The  1902  report  of  the  Hatch  station  says  also :  "There 
are  other  effects  of  drying  on  the  soil  which  prove  very 
destructive  to  the  development  of  lettuce  plants,  although 
we  have  not  observed  this  effect  on  other  species.  On 
lettuce  we  have  observed  this  repeatedly,  and  the  char- 
acteristic results  of  such  drying  are  manifested  in  a 
stunted  growth  and  an  abnormally  colored  and  worthless 
crop.  The  crop  scarcely  ever  attains  more  than  one- 
third  of  its  size.  The  texture  of  the  plant  is  poor,  being 
thick  and  tough,  and  inclined  to  crinkle.  That  this  is 
caused  by  desiccation  alone  is  shown  by  the  fact  that 
wherever  any  drip  fell  from  the  roof  upon  the  soil  during 
the  summer  rains,  the  plants  growing  in  such  places 
were  always  normal.  Distinctly  sharp  lines  can  be  ob- 
served in  a  lettuce  crop  grown  under  such  conditions, 
owing  to  the  difference  in  development  brought  out  by 
desiccation  and  the  presence  of  a  small  amount  of  water 
due  to  dripping.  Instances  have  come  to  our  notice 
where  large  houses  devoted  to  lettuce  have  been  allowed 
to  become  too  dry  in  summer.  If  such  drying  occurs,  the 
soil  can  be  entirely  renovated  by  applying  hot  water  or 
steam  to  it." 

The  drying  of  greenhouse  soils  not  only  increases  the 
difficulty  from  disease,  but  it  is  decidedly  harmful  to  the 
silt  and  clay  types,  which,  after  thorough  desiccation, 
break  up  lumpy  in  the  course  of  preparation  for  planting. 

Summer  mulching. — The  Ohio  station  has  been  con- 
ducting a  series  of  experiments  with  mulches  used  during 
the  summer  period  of  non-cropping.  Horse  manure  has 
been  the  most  effective.  For  seven  years  practically  no 
disease  has  appeared  upon  any  of  the  standard  vegetables 
grown  in  the  experimental  houses.  It  should  be  noted 
that  not  only  was  the  soil  kept  moist,  as  advocated  by 
the  Massachusetts  station,  but  plant  food  and  humus 


SOIL   PREPARATION  79 

were  added  by  the  system  used  at  the  Ohio  station  by 
Green  and  his  associates.  The  experiments,  which  are  of 
such  general  interest  and  value,  are  reported  as  follows 
in  Circular  69 : 

"Three  years  ago  the  Ohio  station  began  an  experiment  to  see 
what  effect  the  use  of  strawy  manure  would  have  on  the  soil  when 
used  as  a  mulch  during  that  part  of  the  summer  when  crops  are 
not  growing  in  the  greenhouses.  This  manure  was  applied  as  soon 
as  the  tomato  and  cucumber  vines  were  removed  from  the  houses, 
or  about  the  first  of  August.  It  was  put  on  to  a  depth  of  five  or  six 
inches  and  spread  evenly  over  the  entire  surface  of  the  beds.  As 
soon  as  it  was  on,  water  was  applied  in  the  form  of  a  spray  until 
the  manure  and  soil  were  thoroughly  wet. 

"The  object  of  this  wetting  was  first  to  leach  the  fertility  of  the 
manure  into  the  soil  and  second  to  wet  the  soil  sufficiently  so  that 
with  the  strawy  mulch  it  would  remain  moist  for  several  days.  The 
operation  of  watering  was  repeated  as  often,  as  needed;  two  or 
three  times  a  week  in  bright  weather. 

"When  we  started  to  plant  the  lettuce,  about  the  middle  of  Sep- 
tember, the  coarse  part  of  the  manure  was  removed  from  the  beds 
and  carried  outside.  The  finer  portion  of  the  manure  was  worked 
into  the  soil  at  the  time  of  spading. 

"It  was  noticeable  that  the  soil  which  had  been  treated  with  the 
mulch  was  in  excellent  condition  when  it  was  worked  up  for  the 
first  crop.  There  were  no  lumps,  as  there  often  are  in  the  soil 
which  has  been  allowed  to  bake  in  the  sun  for  weeks  at  a  time. 
It  was  also  darker  in  color  than  unmulched  soil.  The  lettuce  plants 
which  were  planted  in  this  soil  started  off  nicely  and  grew  rapidly 
and  satisfactorily  in  every  respect.  No  further  application  of 
manure  or  fertilizer  of  any  kind  was  made  for  the  second  or  third 
crops  of  lettuce.  The  growth  of  these  crops  was  very  satisfactory, 
as  was  that  of  the  first  crop.  Liquid  manure  was  applied  to  the 
tomato  plants  when  the  fruit  began  to  ripen.  This  fertility  might 
have  been  applied  in  the  form  of  manure  as  a  mulch,  and  probably 
it  is  best  applied  in  that  way  rather  than  in  the  liquid  form. 

"This  method  of  treating  the  soil  during  the  summer  gave  such 
favorable  results  the  first  season  it  was  tried  that  the  station  in- 
duced several  practical  greenhouse  men  to  try  it  last  season.  One 
firm  at  Toledo,  Ohio,  began  the  use  of  the  summer  mulch  the  same 
season  the  station  began  it,  neither  party  knowing  that  the  other 


80  VEGETABLE  FORCING 

was  trying  this  method  of  soil  treatment.  They  have  continued 
this  practice  and  are  well  pleased  with  the  results.  Of  those  who 
tried  the  mulch,  some  did  not  apply  water  frequently  enough,  thus 
allowing  the  soil  to  become  dry  and  destroying  the  value  of  the 
test.  Others  grew  tomatoes  as  a  fall  crop  on  the  mulched  area 
and  lettuce  on  the  unmulched  area,  thus  preventing  a  fair  com- 
parison. Still  others  mulched  all  of  their  soil,  not  leaving  any  with- 
out mulch  for  comparison.  In  one  case  where  a  careful  mulch  test 
was  made  other  conditions  entered  in  such  a  way  that  safe  con- 
clusions could  not  be  drawn. 

"Taking  the  results  of  the  station  tests,  together  with  the  results 
secured  by  the  Toledo  firm,  and  gleaning  what  information  it  has 
been  possible  to  obtain  from  various  sources,  the  station  does  not 
hestitate  to  recommend  this  treatment  of  soils  to  be  used  for  vegetable 
forcing.  It  must  be  borne  in  mind,  however,  that  no  half-way  or 
slipshod  methods  of  using  the  mulch  will  give  satisfactory  results. 
There  should  be  sufficient  fertility  in  the  manure  to  furnish  enough 
plant  food,  when  leached  into  the  soil,  to  supply  the  three  crops 
of  lettuce.  The  quantity  of  manure  must  be  sufficient  also.  At 
least  5  or  6  inches  must  be  applied.  A  considerable  quantity  of 
coarse  material  in  the  manure,  such  as  straw,  corn  stover,  etc.,  is 
an  advantage.  Fresh  manure  has  been  used  at  the  station  each 
time,  and  while  we  have  had  no  chance  to  see  the  effect  of  the 
use  of  well-rotted  manure,  we  are  satisfied  with  fresh  manure,  as 
we  know  that  it  will  give  good  results. 

"Where  it  is  the  practice  to  mulch  the  cucumber  or  tomato  crop 
the  manure  used  for  that  purpose  can  be  left  on  and  more  added, 
provided  the  cucumbers  or  tomatoes  have  been  free  from  disease. 
In  case  these  crops  have  been  diseased,  it  would  be  advisable  to 
remove  the  mulch  used  on  them  and  to  apply  new  mulch. 

"Frequent  sprinkling  of  the  manure  on  the  beds  is  very  essential, 
and  where  a  mechanical  system  of  watering  is  in  use  this  can  be 
done  thoroughly  and  with  the  expenditure  of  little  time  and  labor. 
When  it  is  necessary  to  water  by  hand  it  will  be  harder  to  get  the 
work  done,  but  it  must  not  be  neglected,  as  failure  is  sure  to  follow 
the  lack  of  sufficient  water  to  properly  leach  the  fertility  of  the 
manure  into  the  soil  and  to  keep  it  moist. 

"When  the  time  comes  to  put  in  the  first  crop,  if  the  soil  is  in 
need  of  humus  the  entire  mulch  may  be  spaded  into  the  soil,  but 
most  greenhouse  soils  do  not  need  the  addition  of  so  much  coarse 


SOIL  PREPARATION  81 

material.  Where  the  soil  is  fairly  well  supplied  with  humus  the 
coarser  part  should  be  taken  off  and  removed  from  the  houses, 
and  the  finer  portion  worked  into  the  soil. 

"We  are  not  prepared  to  say  what  effect  the  use  of  summer 
mulch  may  have  on  the  diseases  affecting  lettuce,  except  that  the 
station  greenhouses  have  been  very  free  from  all  diseases  of  lettuce 
since  we  have  been  using  this  method  of  treating  the  soil.  The 
lettuce  in  the  Toledo  house  has  also  been  practically  exempt  from  these 
diseases  during  the  two  years  they  have  been  mulching.  In  no  case 
where  the  mulch  has  been  used  have  we  observed  an  increase  in  the 
number  of  diseased  plants  over  an  equal  area  not  mulched.  These 
facts,  taken  together  with  results  secured  by  Stone  and  reported  in 
this  circular,  would  lead  us  to  expect  beneficial  rather  than  detri- 
mental results  from  the  proper  use  of  summer  mulch,  in  so  far  as 
it  affects  the  disease  of  lettuce." 

The  Ohio  station  later  compared  manure  mulch  with 
straw  mulch.  The  details  of  the  experiment  are  pub- 
lished on  pages  85  and  86  of  the  official  proceedings  of  the 
Vegetable  Growers'  Association  of  America  for  1909, 
1910  and  1911.  The  yields  varied  little  at  first,  but  the 
fertility  under  the  straw  mulch  became  depleted  quite 
rapidly,  as  shown  by  the  following  report  of  28  tomato 
plants  on  an  area  of  120  square  feet : 

PLOT  1 — MANURE  MULCH 


Variety 

Magnus 

Total  number 
fruits 
326 

Pounds 
102 

Ounces 
n 

Stone  _     . 

299 

104 

13 

Beauty  - 

256 

72 

ft 

Total    881  279  11 

PLOT  2— STRAW  MULCH 

Magnus 234  63  6 

Stone   234  75  11 

Beauty _ 254  76  12 

Total    722  215  13 

The  results  with  lettuce  were  not  so  marked.     There 


82  VEGETABLE  FORCING 

were  16  rows  of  Grand  Rapids  plants.    The  results  were 
as  follows : 

Manure  mulch  Pounds  Ounces 

First  crop 48 

Second  crop 55  0 

Total 103  9 

Straw  mulch  Pounds  Ounces 

First  crop 48  8 

Second  crop 51  2 

Total 99  10 

Notwithstanding  the  striking  results  of  the  Ohio  ex- 
periments, especially  with  regard  to  disease,  mulching 
has  not  become  widely  popular.  It  is  apparently  an  ideal 
method  of  soil  preparation  in  small  houses,  and  it  is 
worthy  of  more  general  trial  in  the  large  commercial 
establishments.  Except  for  the  destruction  of  nematode 
worms,  mulching  might  take  the  place  of  steam  steriliza- 
tion. There  is  also  evidence  that  the  constantly  moist 
condition  of  the  soil  under  the  mulch  is  unfavorable  to 
the  existence  of  nematodes. 

Plowing  and  harrowing. — The  plow  is  becoming  in- 
creasingly popular  in  the  preparation  of  greenhouse  soils. 
Experience  has  demonstrated  its  entire  success.  It  is  a 
labor-saving  device  and  a  relief  to  the  drudgery  of  soil 
preparation.  There  is  no  evidence  to  show  that  spading 
is  any  better  than  plowing,  especially  if  the  soil  is  well 
filled  with  organic  matter.  A  horse  can  be  handled 
better  than  a  team,  and  with  the  light,  level,  easily  tilled 
soil  of  most  greenhouses  a  strong  horse  will  have  no  diffi- 
culty in  drawing  a  two-horse  moldboard  plow,  although 
some  growers  prefer  the  smaller,  one-horse  plows.  After 
plowing,  a  half  section  of  any  of  the  standard  types  of 
harrows  may  be  used  until  the  soil  is  thoroughly  pulver- 
ized. The  surface  should  be  left  smooth  and  even. 
Flankers  or  plank  drags  will  be  found  desirable  for  that 


SOIL   PREPARATION 


83 


purpose.  One  of  the  best  tools  for  greenhouse  work  is 
the  smallest-sized  smoothing  harrow  (Fig.  28)  with  a 
second  leveling  board  adjusted  behind  the  last  row  of 
disks.  When  it  is  desired  to  use  the  plow,  the  lettuce 
should  be  planted  in  long,  narrow  strips,  so  that  when  the 
successional  crops  of  lettuce  are  harvested  the  strips  can 
be  plowed,  harrowed  and  replanted  with  the  minimum 
loss  of  time.  When  horse  implements  are  used  (Fig.  26), 
some  hand  work  will  be  required  along  the  sides  and  ends 
of  the  houses,  to  secure  a  finished  appearance. 

Spading  and  raking. — In  the  smaller  houses  and  in 
most  of  the  large  establishments  the  soil  is  prepared  by 
the  use  of  the  spade  and  rake.  Spading  forks  are  often 
used  instead  of  spading  shovels.  Whatever  the  method 


Fig.  28. — Small  smoothing  harrow. 

employed,  the  soil  should  be  left  in  a  fine  state  of  division. 

Applying  lime. — The  various  commercial  forms  may 
be  used  for  the  treatment  of  greenhouse  soils.  While 
ground  stone  lime  is  most  convenient  to  apply,  unslaked 
stone  lime  and  hydrated  lime  are  used  more  generally 
than  other  forms.  Stone  lime  is  simply  deposited  in 
small  piles  in  the  greenhouses  and  sufficient  water 
applied  to  it  with  a  hose  to  cause  prompt  slaking,  and  the 
lime  is  then  spread  with  a  shovel.  There  is  no  better 
time  to  apply  lime  than  after  plowing  or  spading  and 
before  harrowing  or  raking.  It  should  not  be  mixed 
directly  with  manure  because  it  will  release  the  ammonia. 

No  experiments  have  been  conducted  to  determine  the 


84  VEGETABLE   FORCING 

proper  amount  of  lime  for  greenhouse  soils.  One  pound 
of  unslaked  stone  lime  is  considered  sufficient  for  20 
square  feet  of  space,  and  double  that  amount  will  do  no 
harm.  It  should  be  scattered  evenly  over  the  surface  and 
thoroughly  mixed  with  the  soil.  See  page  64  relating 
to  the  functions  of  lime. 

Applying  fertilizers. — When  commercial  fertilizers  are 
employed  they  are  usually  applied  after  plowing  or 
spading  and  mixed  with  the  soil  by  subsequent  harrow- 
ing or  raking.  Nitrate  of  soda  is  often  used  as  a  top- 
dressing,  applied  either  in  dry  or  liquid  form.  Excessive 
amounts  of  fertilizers  may  cause  curling,  wrinkling  or 
burning  of  the  leaves.  About  l/\.  ton  to  the  acre  of 
mixed  mineral  forms  of  commercial  fertilizers  is  probably 
as  much  as  can  be  used  with  safety  on  any  of  our  green- 
house crops.  One  ounce  of  nitrate  of  soda  to  each  gallon 
of  water  may  be  applied  to  lettuce  and  other  crops  with- 
out danger  of  injury  unless  the  soil  already  contains  a 
large  amount  of  mineral  fertilizers.  For  more  specific 
information,  see  the  discussion  of  fertilizers  in  connection 
with  each  class  of  vegetables. 


CHAPTER  VI 
SOIL  STERILIZATION 

The  necessity  of  sterilization. — In  the  great  commer- 
cial forcing  establishments  the  soil  is  not  changed,  but 
it  is  used  over  and  over  again  with  yearly  additions  of 
stable  manure.  The  amount  of  vegetable  matter  in- 
creases and  the  physical  properties  improve  so  that  in 
most  instances  there  are  serious  objections  to  changing 
the  soil  aside  from  the  labor  of  moving  it.  As  previously 
stated,  vegetable  forcing  is  the  most  intensive  branch  of 
olericulture.  Crops  follow  each  other  in  quick  succes- 
sion. There  may  be  no  rotation  whatever,  for  often  the 
same  crop  is  grown  year  after  year.  With  such  a  system 
of  cropping  there  is  naturally  an  accumulation  of 
destructive  parasites. 

Continuous  cropping  in  the  open  ground  nearly  always 
leads  to  trouble,  and  the  conditions  of  the  greenhouse  are 
even  more  favorable  for  the  breeding  and  multiplication 
of  all  classes  of  parasitic  enemies.  The  accumulation  of 
soil  organic  matter  is  equally  advantageous  to  insect  life 
and  to  fungous  foes.  Soil  desiccation,  inundation,  freez- 
ing, spraying,  mulching  and  fumigating  have  their  values, 
and  may  be  the  means  of  checking  or  even  controlling 
many  of  the  foes,  but  other  measures  have  become  a 
necessity  in  most  of  the  large  commercial  houses.  In 
fact,  soil  sterilization  is  now  universally  regarded  as 
essential  to  success,  although  there  are  instances  where 
splendid  crops  have  been  grown  for  many  years  without 
resorting  to  sterilization. 

There  is  a  wide  difference  of  opinion  among  successful 
and  intelligent  growers  regarding  the  value  of  steriliza- 
tion. Some  consider  it  an  essential  operation  to  sterilize 

85 


86 


VEGETABLE   FORCING 


the  soil  every  year  as  a  matter  of  insurance,  though  there 
may  be  little  evidence  of  the  presence  of  destructive 
insects  or  diseases.  Others  practice  sterilization  only 
when  they  regard  it  as  absolutely  necessary,  and  they 
may  have  large  ranges  in  which  the  soils  of  some  houses 
are  sterilized  every  year,  and  others  in  which  the  soils 
have  never  been  sterilized.  Conditions  are  so  variable 
that  no  rule  can  be  laid  down  for  all  growers  in  regard  to 
the  desirability  or  importance  of  soil  sterilization.  It  is 
certain,  however,  that  hundreds  of  growers  will  be  com- 
pelled to  resort  to  this  practice  unless  desiccation  (for 


Fig.  29. — Pan  steam   sterilization   in    operation   at  the   Indh 
Experiment    Station. 


Agricultural 


nematodes)  and  mulching  are  found  to  be  satisfactory 
and  become  more  generally  employed. 

Methods. — Although  dry  heat  and  hot  water  are  em- 
ployed to  some  extent,  steam  and  the  formalin  or  for- 
maldehyde drench  are  the  methods  in  most  general  use; 
of  these  two  methods  steam  is  very  much  the  more 
popular  in  the  largest  commercial  establishments,  though 
the  hot  water  method  is  gaining  in  popularity.  Steam- 
ing, when  properly  managed,  destroys  all  animal  life  as 
well  as  fungous  and  bacterial  enemies.  The  nematode, 


SOIL   STERILIZATION  87 

which  is  considered  the  most  serious  of  the  animal  foes, 
is  repressed  both  in  the  egg  and  worm  state  by  thorough 
steaming.  Weed  seeds  are  also  destroyed  and  plant 
food  is  made  more  available.  Several  investigators  have 
shown  that  steam  sterilization  increases  the  amount  of 
soluble  or  available  nitrogen,  potash  and  phosphoric 
acid.  It  also  increases  the  absorptive  power  of  the  soil 
for  water.  Some  of  the  experiments  indicate  that  steam 
sterilization  tends  to  develop  certain  toxics  and  also  in- 
creases the  acidity  of  the  soil.  If  lime,  however,  is 
applied  before  the  soil  is  sterilized,  there  need  be  no  fear 
of  any  harmful  effect. 

In  this  connection,  Stone  and  Smith  state  the  follow- 
ing in  Bulletin  55  of  the  Massachusetts  station :  "In  the 
numerous  crops  of  cucumbers,  tomatoes  and  lettuce 
which  we  have  grown  in  sterilized  earth  we  have  never 
noticed  anything  of  a  detrimental  nature,  but  on  the 
other  hand  a  decidedly  beneficial  effect  as  the  result  of 
sterilization.  Not  only  is  this  shown  in  the  difference  in 
color  which  the  plants  take  on,  but  in  an  appreciable 
acceleration  of  their  growth.  We  have  repeatedly  run 
parallel  cultures  of  sterilized  and  unsterilized  soil  and 
have  invariably  noticed  these  effects  on  cucumbers  and 
lettuce." 

Rudd,  whom  we  have  already  quoted  as  having  tried 
the  sterilized  method,  says  :* 

"It  has  long  been  known  among  practical  gardeners  that  heating 
the  soil  produces  beneficial  results.  Every  greenhouse  soil  contains 
humus  or  vegetable  mold,  and  it  is  recognized  by  vegetable  physiol- 
ogists that  the  presence  of  humus  in  the  soil  plays  an  important 
part  in  the  assimilation  and  plant  growth,  but  its  efficiency  depends 
partly  upon  the  stage  of  decomposition  at  which  it  has  arrived.  It 
has  been  shown  by  experiments  in  which  plants  are  treated  in  one 
case  with  humus  in  the  raw  condition,  and  in  the  other  with  humus 
which  has  been  subjected  to  the  action  of  steam  for  several  hours 

*  American  Florist,  Vol.  IX,  p.  171-197. 


88  VEGETABLE  FORCING 

at  a  temperature  of  212  degrees,  that  there  is  considerable  difference 
in  the  yield  of  the  crop.  It  has  been  found  that  the  same  quantity 
of  soil,  after  the  action  of  heat,  yields  a  crop  many  times  in  excess 
of  the  former  or  untreated  soil.  In  other  words,  by  heating  we  con- 
vert the  humus  compounds  in  the  soil  into  a  more  available  form 
for  the  utilization  of  the  plant.  That  heating  of  the  soil  gives  rise 
to  some  changes  is  shown  by  its  darker  color  and  more  porous  con- 
dition, and  it  is  undoubtedly  due  to  these  changes  which  have  taken 
place  in  the  humus  compounds,  which  account  for  the  accelerated 
and  vigorous  growth  of  the  plants. 

"Another  feature  which  is  characteristic  of  sterilized  soils  is  the 
unusual  occurrence  of  humus-loving  plants,  or  saprophytes,  that  grow 
upon  it,  which  is  a  good  indication  that  the  organic  matter  contained 
in  the  soil  has  undergone  changes  through  the  action  of  the  heat. 
We  have  ourselves  observed  more  than  once  certain  species  of 
saprophytic  fungi  growing  upon  our  steamed  beds  which  have  never 
shown  any  tendency  to  grow  in  unheated  soil,  although  with  the 
exception  of  being  steamed  the  soil  was  exactly  the  same  as  that 
upon  which  they  never  appeared." 

Evil  results  sometimes  follow  the  use  of  steam,  prob- 
ably because  of  injurious  effects  upon  the  physical 
properties  of  the  soil,  especially  when  the  soil  has  not 
been  properly  handled  after  sterilization.  All  things 
considered,  steaming  is  the  most  complete,  effectual 
and  practical  method  of  soil  sterilization. 

Formalin,  however,  has  a  useful  place  in  the  manage- 
ment of  many  greenhouses.  While  the  usual  strengths 
have  little  effect  upon  the  animal  life  of  the  soil  and  do 
not  destroy  nematode  eggs,  many  of  the  diseases  may  be 
controlled  by  the  use  of  this  disinfectant.  Small  areas 
of  soil  sometimes  show  infestation  at  midwinter,  and 
they  may  be  drenched  with  formalin  when  it  would  not 
be  practicable  to  use  steam.  Again,  there  are  hundreds 
of  small  houses  heated  by  flues  or  hot  water  where  steam 
is  not  available  and  formalin  can  be  used  to  advantage. 
Its  use  is  not  so  harmful  to  silty  and  clay  soils,  the 
structure  of  which  is  often  injured  by  steaming. 


SOIL  STERILIZATION  89 

Steam  Sterilization 

Temperature  required. — Definite  information  gained 
from  experiments  relating  to  this  question  is  contained  in 
Bulletin  55  of  the  Massachusetts  station,  from  which  is 
quoted  the  following : 

"Our  experiments  upon  this  point  were  numerous,  and  they  were 
made  with  earth  containing  abundance  of  nematodes  of  various 
species  in  all  stages  of  development.  For  the  sake  of  convenience 
we  will  designate  these  experiments  as  a,  b,  c,  etc.  In  all  of  these 
experiments  we  employed  cucumbers  in  pots  of  various  sizes  (from 
4  inches  to  10  inches),  and  the  plants  were  left  until  they  were 
sufficiently  large  to  show  root  galls  upon  them  if  nematodes  were 
present  in  the  soil.  In  every  case  except  'a'  the  pots  containing  the 
infested  earth  were  sterilized  in  an  Arnold  steam  sterilizer,  and 
when  moderate  heating  was  required  they  remained  in  the  sterilizer 
only  a  few  minutes. 

"The  earth  in  experiment  'a'  was  part  of  a  large  lot  which  was 
sterilized  in  a  box  by  means  of  steam  from  a  boiler.  In  every  in- 
stance numerous  microscopic  examinations  were  made  of  the  soil 
and  roots  of  the  plant  in  order  to  determine  whether  nematodes 
were  present.  The  non-parasitic  species  are  generally  present  in  al- 
most every  soil,  and  their  presence  can  very  often  be  suspected  by 
the  coloration  of  the  root.  They  are  generally  found  on  the  older 
parts  of  the  root  near  the  surface  of  the  soil,  as  indicated  by  the 
dirty  brown  color  of  the  epidermal  tissue.  The  experiments  are  as 
follows : 

"Exp.  a.  Six  4-inch  pots  were  filled  with  infested  earth  which  had 
been  heated  to  212  degrees.  The  pots  were  also  sterilized  and  the 
cucumber  seeds  after  soaking  12  hours  in  water  were  placed  for 
10  minutes  in  a  saturated  solution  of  corrosive  sublimate,  and  be- 
fore using  were  rinsed  with  sterilized  water.  During  germination 
and  the  growth  of  the  plants  they  were  always  watered  with  filtered 
water.  Hence  all  source  of  contamination  was  eliminated.  Results, 
no  nematodes. 

"Exp.  b.  Six  plants  treated  as  above.    Result,  no  nematodes. 

"Exp.  c.  Twelve  pots  of  cucumbers,  the  seeds  of  which  were 
treated  as  in  Exp.  'a'  and  the  plants  watered  with  sterilized  water. 


90  VEGETABLE  FORCING 

Instead  of  the  soil  in  the  pots  all  being  heated  to  212  degrees  they 
received  the  following  various  degrees  of  heat  before  planting : 

No.  of  pot  12  34          567  8          9        10      11       12 

Temperature      114      118      127      140      147      150      159      161      163     163     170    176 

"Result:  Nos.  1,  2  and  3  all  damped  off.  The  remainder  were 
perfectly  free  from  the  damping-off  fungus  and  nematodes. 

"Exp.  d.  Sixteen  pots  of  cucumbers  were  treated  the  same  as  *c.' 

No.  of  pot  1       23       4       5       6       7       8       9       10    11      12     13    14    15    16 

Temperature  147  149  154  159  163  167  16?  172  176  183  185  186  192  194  196  199 

"Result :    No  nematodes. 

"From  these  experiments,  which  only  represent  about  one-half 
of  what  was  done,  it  appears  that  a  very  high  temperature  is  not 
necessary  in  order  to  free  infested  soil  of  nematodes.  The  number 
of  degrees  of  heat  necessary  is  about  140  degrees,  but  as  a  matter  of 
safety  the  temperature  should  go  above  this,  inasmuch  as  in  large 
areas  of  soil  the  distribution  of  heat  is  always  unequal,  and  while 
one  portion  may  be  heated  as  high  as  190  degrees  another  portion 
may  not  exceed  110  degrees.  The  conclusion,  then,  that  the  soil 
must  be  heated  under  pressure  to  a  temperature  of  225  or  235  de- 
grees in  order  to  kill  nematode  life  is  therefore  not  valid  in  all 
cases.  These  experiments  were  made  with  sufficient  care  and  were 
repeated  often  enough  with  the  same  results  to  consider  them  trust- 
worthy." 

Stone  has  since  stated,  and  his  statement  is  based  upon 
further  research,  that  the  soil  should  be  heated  to  a 
temperature  of  180  degrees  and  that  212  degrees  is  better. 
This  corroborates  the  views  of  growers  who  have  been 
successful  in  steaming  soils.  While  140  degrees  will 
kill  insects  and  nematode  eggs,  there  are  disease  germs 
which  require  higher  temperatures.  A  high  temperature 
is  also  necessary  to  secure  the  thorough  permeation  of 
the  soil  particles  which  harbor  and  protect  insects  and 
disease  germs. 

Time  required. — Steam  sterilization  is  really  the  cook- 
ing of  every  particle  of  soil,  and  considerable  time  is 
required  to  accomplish  this.  Steam  under  pressure 
passes  through  open,  coarse,  sandy  soils  more  rapidly 


SOIL   STERILIZATION  91 

than  through  compact  silts  and  clays.  Again  the  time 
required  will  depend  upon  the  pressure  and  volume  of 
steam,  and  the  volume  of  soil  to  be  sterilized.  In  most 
of  the  greenhouses  using  high  pressure  steam  with  100 
horse  power  boilers  or  more,  sterilization  goes  on  for  an 
hour.  One  large  establishment  with  a  350  horse-power 
boiler  regards  45  minutes  as  ample  time.  Others  with 
high  pressure  steam  sterilize  for  an  hour  and  a  quarter, 
while  occasionally  an  hour  and  a  half  is  regarded  as 
necessary.  The  safe  practice  of  one  very  careful  grower 
is  to  continue  steaming  for  half  an  hour  after  the  soil 
reaches  a  temperature  of  212  degrees. 

The  shortest  period  of  sterilization  is  used  by  a  very 
large  establishment  at  Toledo.  This  firm  uses  a  350 
horse-power  boiler  and  sterilizes  for  only  10  minutes 
with  a  pressure  of  90  degrees  at  the  boiler.  In  this  case 
the  peg  method  is  employed  as  described  later  in  this 
chapter.  It  is  claimed  that  the  plan  has  given  entire 
success.  With  low  pressure  steam  a  much  longer  time 
is  required  to  heat  all  the  particles  of  soil  to  the  re- 
quired temperature.  Four  or  five  hours  is  not  too  much 
time,  and  then  the  beds  should  be  covered  over  night  to 
retain  the  heat. 

Boiler  and  pressure. — Large  boilers  and  high  pressure 
steam  are  advantageous  in  every  respect.  Less  time  is 
required  to  raise  the  temperature  of  the  soil  to  the  re- 
quired temperature  than  with  small  boilers  and  low 
pressure  steam.  A  large  volume  of  steam  under  high 
pressure  makes  it  possible  to  sterilize  a  larger  area  at  one 
time,  and  this  is  usually  a  matter  of  great  economy  from 
the  labor  standpoint.  Boilers  of  300  horse-power  or  more 
are  used  for  the  steaming  of  soils,  although  much  smaller 
boilers  are  often  employed. 

One  of  the  largest  and  most  successful  greenhouse 
plants  maintains  a  boiler  pressure  of  90  to  100  pounds 
for  45  minutes.  Many  establishments  sterilize  with  a 


92  VEGETABLE  FORCING 

boiler  pressure  ranging  from  50  to  70  pounds.  A  highly 
successful  grower  has  found  20  pounds  satisfactory  when 
pans  are  used  over  loose  soil. 

Preparing  soil. — Previous  to  sterilizing  with  either 
steam  or  formalin,  the  soil  should  be  manured  and 
plowed  or  spaaed  ready  for  planting.  If  lime  is  to  be 
used,  it  also  should  be  applied  before  the  soil  is  sterilized. 

It  is  important  for  the  soil  to  be  rather  open  in  struc- 
ture, so  that  the  steam  will  penetrate  every  particle.  It 
should  also  be  quite  moist,  but  not  wet.  More  formalin 
is  required  in  dry  soil,  and  the  results  in  dry  soil  with 
either  method  are  unsatisfactory.  The  various  organ- 
isms are  in  a  live  state  or  more  active  in  moist  soils,  and 
in  this  condition  they  succumb  more  quickly  to  the 
sterilizing  agents. 

Devices  for  sterilizing. — Various  devices  are  employed 
for  sterilizing  by  steam.  Among  them  may  be  mentioned 
boxes,  pans,  perforated  iron  pipe,  perforated  pipe  pegs 
and  ordinary  drain  tile.  In  the  selection  of  a  plan  there 
are  two  main  considerations,  viz.,  efficiency  and  economy. 
A  plan  may  be  very  efficient  but  highly  expensive, 
especially  in  regard  to  the  amount  of  labor  involved. 
There  is  very  little  specific  information  on  the  relative 
efficiency  of  the  various  plans,  and  it  is  probably  not  so 
much  a  question  of  plan  as  of  thoroughness  and  good 
management.  All  of  the  five  devices  which  will  now  be 
described  have  been  used  with  success. 

Boxes. — During  the  earliest  days  of  steam  sterilization, 
boxes  were  used  exclusively.  They  varied  greatly  in  size, 
proportions  and  construction,  but  fundamentally  they 
were  similar.  The  general  scheme  was  to  make  wooden 
boxes  of  convenient  size,  and  to  place  perforated  pipe  in 
the  bottom  of  them.  The  boxes  were  covered  to  confine 
the  steam,  and  the  joints  were  made  as  tight  as  possible. 
The  pipe  in  the  bottom  of  the  boxes  was  usually  1  inch  or 
14  inches  in  size  and  connected  with  headers  2  inch 


SOIL  STERILIZATION  93 

larger.  They  were  placed  12  to  15  inches  apart  and 
closed  at  the  ends  opposite  the  headers.  The  holes  in  the 
pipe  were  usually  l/%  or  l/^  inch  in  diameter,  about  a  foot 
apart,  and  turned  down  to  prevent  them  from  being 
stopped  with  dirt.  It  is  probable  that  the  boxes  should 
never  be  more  than  a  foot  deep.  Two-inch  drain  tile  may 
be  substituted  for  iron  pipe.  With  an  ample  volume  of 
steam  under  high  pressure  thorough  sterilization  can  be 
effected  in  an  hour.  The  boxes  may  be  covered  with 
heavy  canvas  or  hotbed  sash.  When  a  large  amount  of 
soil  is  to  be  sterilized  there  should  be  at 'least  two  boxes 
to  facilitate  handling  the  soil.  While  the  box  method  is 
convenient  for  sterilizing  potting  soils,  flats,  tools,  etc.,  it 
is  now  seldom  used  in  vegetable-growing  establishments 
because  of  the  excessive  cost  of  handling  the  soil. 

Pans. — The  inverted  pan  method  is  used  by  a  great 
many  large  growers,  especially  in  the  Cleveland  district. 
It  is  regarded  by  some  as  not  so  thorough  as  the  tile  and 
perforated  pipe  plans,  although  some  of  the  most  careful 
and  successful  growers  are  unwilling  to  concede  this 
point.  There  are  examples  of  perfect  pan  sterilization  of 
soils  which  had  become  most  seriously  infested  with 
nematodes  and  many  other  destructive  pests.  The  pan 
method  does  not  require  any  handling  of  the  soil,  and 
this  is  unquestionably  its  greatest  advantage.  The  plan 
is  becoming  more  popular  every  year.  It  is  particularly 
valuable  for  open,  porous  soils  which  are  easily  pene- 
trated by  steam. 

Galvanized  iron  pans  are  the  most  durable.  They  may 
be  of  any  convenient  size.  Fig.  29  shows  a  pan  which  is 
used  at  Purdue  University.  Sometimes  they  are  only 
4  feet  wide  and  8  to  12  feet  long.  The  pans  are  usually 
6  to  8  inches  deep.  Pipe  connection  is  made  at  the  side 
or  end  as  shown  in  the  illustration,  or  in  the  bottom  of 
the  middle  of  the  sterilizer  with  an  ell  and  a  nipple  on  the 
outside  for  the  attachment  of  a  hose  of  inch  size  or  larger. 


94 


VEGETABLE  FORCING 


The  pan  is  inverted  and  the  sharp  edges  forced  2  to  4 
inches  into  the  ground.  The  pans  should  be  of  the 
proper  proportions  to  work  conveniently  between  posts 
and  walks.  They  are  simply  shifted  along  the  beds  as 
fast  as  the  soil  is  sterilized.  In  large  greenhouses  it  is 
important  to  have  at  least  half  a  dozen  pans,  for  two  men 
can  easily  tend  to  this  number.  In  small  houses  heated 
by  hot  water  it  is  possible  to  connect  a  steam  hose  with 
a  portable  engine,  as  shown  in  Fig.  30. 


Fig.  30. — A  portable  steam  engine  may  be  used  for  sterilizing  small  houses. 

A  prominent  Ohio  grower  has  devised  an  apparatus  for 
lifting  and  shifting  soil-sterilizing  pans  which  has  proven 
highly  satisfactory.  He  has  kindly  furnished  the  follow- 
ing description : 

"It  consists  of  a  square  wooden  frame  slightly  larger  than  the 
pan  and  about  30  inches  high,  with  a  small  car  wheel  at  each  corner. 
Across  the  top  of  the  frame  is  fitted  a  1^-inch  pipe  with  a  bearing 
at  each  end,  and  on  one  end  a  worm  gear  with  crank.  Near  each 
end  of  this  pipe  a  ^-inch  hole  was  drilled,  and  a  %-inch  wire  tiller 
rope  was  passed  and  fastened.  This  cable  must  be  of  sufficient 
length  to  reach  across  the  frame,  over  a  pulley  at  each  corner  of 
the  frame  at  that  end,  and  down  to  a  hook  in  the  corner  of  the  pan. 
Thus,  when  the  cables  are  properly  adjusted  as  to  length,  the  turn- 
ing of  the  pipe  by  means  of  the  worm  gear  will  wind  the  cable  and 


SOIL  STERILIZATION 


95 


lift  the  pan  at  all  four  corners,  transferring  the  weight  to  the  car 
wheels.  The  whole  apparatus  is  then  rolled  along,  the  width  of  the 
pan,  and  if  the  worm  gear  is  well  oiled,  a  sharp  throw  of  the  crank 
will  cause  it  to  spin  in  lively  fashion,  lowering  the  pan  to  its  new 
position.  The  gear  is  intended  for  raising  short  lines  of  light  venti- 
lators, but  fills  this  purpose  admirably.  Steam  is  delivered  in  the 
center  of  the  pan  by  means  of  a  hose  from  a  temporary  steam  line 
into  a  pipe  running  lengthwise  beneath  with  a  few  holes  drilled 
through  to  spread  the  steam." 

Perforated  pipe. — The  perforated  pipe  system  is 
popular  and  highly  satisfactory.  There  are  many 
modifications  in  its  installment,  but  the  general  plan  is  to 
provide  gangs  or  sets  of  perforated  iron  pipe.  These  may 


Fig.  31. — Peg  or  rake  steam   sterilizer  used   by  some   growers   at   Toledo,   Ohio. 

be  25  to  90  feet  long,  depending  upon  the  supply  of  steam, 
size  of  house  and  number  of  men  available  to  move  them. 
Fifty-foot  lengths  are  convenient  to  handle.  The  number 
of  pipes  in  each  set  is  variable,  although  five  is  a  common 
number.  The  perforated  pipes  are  usually  1*4  inches  in 
size,  although  1^-inch  pipe  is  used  in  some  of  the  largest 
greenhouses  where  the  gangs  are  very  long.  The  holes 
are  */£  or  *4  of  an  inch  in  size,  sometimes  larger,  and 
about  a  foot  apart.  The  pipes  are  laid  16  to  18  inches 
apart  and  connected  with  a  2-inch  header. 

A  successful  grower  at  Irondequoit,  N.  Y.,  uses  a  2- 


96  VEGETABLE  FORCING 

inch  header  with  six  l*4-inch  outlets  or  laterals,  placed  17 
inches  apart,  the  laterals  being  45  feet  in  length  and  per- 
forated with  ^/6-inch  holes  10  inches  apart.  The  header 
is  placed  crosswise  of  the  bed  to  be  sterilized,  with  the  lat- 
erals running  lengthwise.  The  pipes  are  buried  to  a  depth 
of  about  6  inches  and  the  whole  bed  is  then  covered  with 
a  heavy  canvas.  The  header  is  connected  with  the  heat- 
ing system  at  the  center,  giving  three  lines  on  each  side. 
The  Irondequoit  grower  referred  to  has  also  found 
ordinary  2-inch  corrugated  galvanized  conductor  pipe 
highly  satisfactory.  The  pipes  are  light,  easily  forced 
together  and  they  cool  very  quickly  so  that  shifts  may  be 
made  without  discomfort.  The  perforations  may  be  made 
with  a  ten-penny  nail.  It  is  desirable  to  turn  the  pipes 
with  the  perforations  down,  or  to  cover  them  with 
burlap  to  keep  dirt  out  of  the  holes.  The  perforated  pipes 
are  simply  buried  in  the  ground  beds  under  6  or  7  inches 
of  soil,  and  the  bed  is  covered  with  heavy  canvas  to  retain 
the  heat.  In  a  very  large  range  at  Ashtabula,  Ohio,  eight 
gangs  of  pipe  are  used  to  keep  quite  a  large  force  of  men 
busy  shoveling  soil  and  shifting  the  pipes.  A  300  horse- 
power engine  is  used  in  this  establishment. 

Perforated  pegs  (Figs.  31  and  32)  are  used  successfully 
in  some  sections.  This  is  sometimes  called  the  "steam 
rake"  or  the  "steam  harrow"  method.  These  devices 
may  be  made  of  any  convenient  size  and  dimensions. 
The  feed  lines  and  arms  are  composed  of  a  series  of  re- 
ducing nipples  with  T's  located  so  that  the  pegs  will  be 
about  8  inches  apart,  giving  the  appearance  of  a  harrow. 
The  arms  of  the  feed  lines  may  start  with  24-inch  pipe, 
the  second  joint  ^/2-inch  and  the  third  %-inch.  The 
^4-inch  pegs  are  flattened  at  one  end  into  the  form  of  a 
wedge  with  a  3-16-inch  perforation  at  the  lower  end  for 
the  escape  of  steam.  A  heavy  1-inch  hose  connects  with 
the  steam  pipe  that  leads  to  the  boiler.  The  sterilizer  is 
forced  into  the  ground  and  covered  with  canvas  which 


SOIL  STERILIZATION  97 

extends  12  feet  or  more  behind  it.  Four  such  devices  are 
in  operation  at  the  same  time  in  a  large  range  at  Toledo, 
and  they  are  moved  every  10  minutes.  Two  men  can 
easily  take  care  of  this  number  and  also  rake  down  the 
beds  as  rapidly  as  the  sterilizers  are  moved.  It  is  a  much 
less  laborious  system  than  when  perforated  pipes  are 
used,  as  explained  on  another  page  in  this  chapter. 

Tile. — The  tile  method  has  some  advocates,  although 
it  has  seldom  met  with  favor  in  large  houses.  In  prin- 
ciple and  practice  the  system  is  similar  to  the  perforated 
pipe  plan  of  sterilization,  except  that  the  tiles  are  some- 
times laid  permanently  and  not  disturbed  from  year  to 
year.  When  tiles  are  employed  they  may  also  be  service- 


Fig.  32. — Peg    steam    sterilizer    in    operation    at    Toledo,    Ohio. 

able  in  sub-irrigation,  and  be  used  to  raise  soil  tempera- 
tures by  the  admission  of  steam  whenever  this  is  con- 
sidered desirable.  When  laid  permanently  the  initial  cost 
is  rather  heavy,  but  there  would  be  a  great  saving  in 
labor  when  a  long  term  of  years  is  considered. 

Frequency  of  sterilization. — When  sterilization  is  once 
started,  nearly  all  growers  seem  to  favor  attending  to  it 
every  summer.  One  successful  grower  has  found  every 
two  or  three  years  sufficient.  Sterilization,  however,  is 
universally  regarded  in  the  same  light  as  fire  insurance, 


98 


VEGETABLE  FORCING 


and  most  growers  feel  that  it  is  unwise  to  take  chances 
of  losses  that  can  be  averted  by  proper  methods  of 
disinfection. 

After-treatment.  —  Soils  that  have  been  sterilized  by 
either  steam  or  formalin  require  careful  after-treatment. 
This  is  particularly  true  of  silty  and  clay  soils,  the 
structure  of  which  is  affected  by  these  treatments. 
They  become  more  compact,  and  their  water-holding 
power  is  increased  so  that  there  is  danger  of  overwater- 
ing  such  soils  until  normal  relations  become  established. 
As  soon  as  dry  enough  the  surface  of  the  ground  should 
be  stirred  and  water  applied  with  extreme  caution  after 
the  plants  have  been  set. 


7777 


Formalin  Sterilization 

Strength  of  solution. — Most  growers  who  employ  this 

method  of  steri- 
1  i  z  a  t  i  o  n  use 
either  three  or 
four  pints  of 
commercial  for- 
malin of  40  per 
cent  purity  to 
50  gallons  of 
water.  Two 
pints  often 
prove  effective, 
but  a  stronger 
solution  is  gen- 
erally  pre- 
ferred.  Rhizoc- 
tonia  or  rosette 
of  lettuce  may 
be  controlled 
with  less  than 
two  pints  to  50 


Out/et 

(Z 


In/et 


Fig.  33. — Apparatus  for  formalin  sterilization.  (W.  T. 
— Water  tank.  F.  T. — Formalin  tank.  G. — Water-glass 
gauge  to  show  quantity  of  formalin.  A. — Air  cock.  V. — 
Valve.  F. — Funnel.  £. — Air  pipe  to  maintain  same 
pressure  in  both  tanks.  D. — Drain-off  cock.  H.  and 
R. — Supports.  B. — Base.  O. — Outlet.  S. — Glass  tube 
through  which  the  formalin  drops  to  tank  below.) 


SOIL  STERILIZATION  99 

gallons,  but  the  weaker  solutions  do  not  seem  to  be 
effective  against  many  other  diseases. 

Application. — There  is  universal  agreement  that  one 
gallon  of  the  solution  should  be  applied  to  each  cubic 
foot  of  soil  in  order  to  thoroughly  saturate  every  particle. 
It  may  be  applied  by  means  of  watering  cans,  sprayers, 
barrels  with  hose  attachments,  overhead  system  of  water- 
ing, special  devices  and  through  the  regular  water  pipes 
of  the  house,  and  at  different  times,  if  the  soil  does  not 
absorb  the  solution  promptly. 

The  watering-can  method  is  slow  and  tedious  and 
should  not  be  used  except  in  small  houses.  Sometimes 
barrels  are  supported  on  trellises  5  or  6  feet  above  ground 
and  bibs  inserted  for  hose  attachment.  A  frame  10  feet 
square  may  be  shifted  from  place  to  place,  and  this  will 
mark  each  area  which  should  receive  a  barrel  of  the 
solution.  In  soils  that  do  not  absorb  water  rapidly  it 
will  be  necessary  to  return  to  the  same  areas  two  or  three 
times  in  order  to  apply  the  full  amount  and  to  avoid 
puddling  the  surface. 

The  pipes  used  in  the  overhead  system  of  watering 
have  been  employed  sometimes,  but  the  lack  of  uniform 
distribution  is  an  objection  to  this  plan. 

B.  H.  Thorne,  in  the  1909  Report  of  the  Vegetable 
Growers'  Association  of  America,  gives  the  following 
description  of  the  formalin  tank  which  is  shown  in 
Fig.  33: 

"In  order  to  get  the  right  proportions,  run  clear  water  through 
the  tank  into  a  barrel  of  known  capacity  and  time  it,  then  run  water 
through  the  formalin  tank  under  the  same  pressure  as  the  water, 
regulating  it  by  the  valve  at  S  until  the  formalin  tank  runs  one  pint 
of  formalin  to  25  gallons  of  water.  The  water  tank  should  be  at 
least  ten  times  the  capacity  of  the  formalin  tank  in  order  to  furnish 
air  to  take  the  place  of  the  formalin  used. 

"The  apparatus  should  be  pumped  full  of  air  before  it  is  used. 
A  bicycle  pump  attached  at  A  will  do  it  nicely.  The  mixture  will 


100  VEGETABLE  FORCING 

be  as  thoroughly  done  as  in  ordinary  spraying.     Be  sure  to  have  the 
outlet  at  the  faucet  end  from  the  formalin  entrance  at  S." 

Mr.  Thorne  also  gives  in  the  same  report  the  following 
description  of  a  formalin  mixer,  making  it  possible  to 
apply  the  solution  through  the  regular  water  pipes : 

"The  formalin  mixer  is  made  of  two  ordinary  kitchen  range 
tanks,  one  above  and  at  one  side  of  the  other.  The  upper  one  holds 
the  formalin  and  the  lower  one  is  the  mixer.  The  tops  of  both  are 
connected  by  a  small  pipe  with  a  valve  in  it.  This  pipe  is  to  equalize 
the  pressure  in  both  tanks  by  the  passage  of  air  back  and  forth. 

"The  formalin  tank  has  a  glass  water  gauge  at  the  bottom  to  show 
when  the  formalin  gets  too  low,  and  the  lower  tank  a  gauge  at  the 
top  to  show  when  the  water  gets  too  high.  From  the  bottom  of  the 
formalin  tank  a  K-inch  pipe  goes  down  to  meet  the  pipe  from  the 
waterworks  running  into  the  bottom  of  the  lower  tank.  Connect- 
ing the  end  of  the  J4~inch  pipe  with  the  water-works  pipe  are  a 
needle  valve  to  regulate  the  flow  of  formalin,  and  another  glass 
gauge  to  show  that  the  formalin  is  running  properly. 

"The  formalin  and  water  are  mixed  in  the  lower  part  of  the  lower 
tank  by  the  moving  water  coming  in  continuously  and  the  mixture 
runs  out  about  one-third  of  the  way  up  back  into  the  water-works 
system.  The  apparatus  is  connected  to  the  regular  watering  system 
through  a  by-pass. 

"In  order  to  get  the  right  proportions  of  formalin  and  water,  run 
50  gallons  of  water  through  the  apparatus  and  time  it,  and  then 
regulate  the  needle  valve  to  run  out  two  pounds  in  the  same  time. 
An  air-pump  is  needed  to  force  air  into  the  upper  tank  to  force 
back  the  water  in  the  lower  tank  when  it  gets  too  full.  With  this 
apparatus  one  man  can  apply  the  mixture  as  fast  as  the  water  runs." 

It  is  also  important  to  spray  walks,  benches,  flats  and 
tools  with  formalin. 

After  sterilizing  with  formalin,  planting  should  be 
deferred  10  days  to  two  weeks  because  the  plants  will  be 
injured  if  set  too  soon. 

Cost. — So  many  factors  enter  into  the  expense  of  steril- 
izing with  formalin  that  it  is  difficult  to  give  definite  cost 
figures.  When  a  mixer  was  used,  Thorne  claimed  that 
the  solution  and  its  application  cost  about  two-fifths  of  a 


SOIL  STERILIZATION  J.  J '     '     j 

cent  a  cubic  foot,  provided  the  formalin  was  bought  in 
barrel  lots  at  wholesale  prices.  A  later  circular  (No.  151) 
of  the  Ohio  station  places  the  cost  of  material  for  only 
one  house  of  3,000  square  feet  at  $21.  This  is  much  above 
the  required  expenditure  for  steam  sterilization  as 
estimated  by  the  same  station,  viz.,  by  perforated  pipe 
method  $15.40  for  3,000  square  feet,  and  inverted  pan 
method  $12.20  for  3,000  square  feet.  A  prominent  Cleve- 
land grower,  who  has  about  four  acres  of  glass,  states 
that  two  men  with  four  pans  will  sterilize  3,000  square 
feet  in  two  days,  the  labor  costing  $8,  and  fuel  $6,  or  $14 
for  this  area.  An  account  was  kept  in  a  well-managed 
house  at  Irondequoit,  N.  Y.,  where  perforated  pipes  were 
used,  and  the  actual  cost  in  a  30  by  180  foot  house — 5,400 
square  feet  of  space — was  $22.50. 

Hot  Water  Sterilization 

This  method  of  sterilization  has  been  attracting  atten- 
tion for  several  years.  Waid,  in  a  recent  issue  of  the 
Market  Growers'  Journal,  writes  as  follows  on  this  subject : 

"Recent  accumulative  evidence  has  demonstrated  the  value  of 
hot  water  as  a  treatment  for  greenhouse  soil,  especially  when  the 
soil  is  infested  with  nematodes.  To  be  effective,  however,  it  is  nec- 
essary that  it  be  forced  into  the  soil  to  a  considerable  depth,  6  or  8 
inches,  and  at  a  very  high  temperature.  A  grower  at  Grand  Rapids, 
Mich.,  used  hot  water  on  most  of  his  greenhouse  soil  this  season 
with  very  satisfactory  results.  He  heated  the  water  in  one  boiler, 
then  forced  it  into  a  second  boiler  in  which  the  water  was  kept 
at  a  temperature  of  238  to  240  degrees,  under  a  pressure  of  15 
pounds.  It  required  two  days  for  five  men  to  treat  one  house  275 
by  34  feet.  About  five  tons  of  soft  coal  was  consumed  per  house. 
The  total  cost  of  treating  one  house  was  about  $50.  One  bed  of  the 
same  size  was  treated  with  $100  worth  of  formaldehyde.  The  hot 
water  treated  beds  gave  the  best  and  heaviest  crops.  The  soil  was 
a  light  sand.  It  would  seem  that  so  much  water  might  'puddle*  a 
heavy  soil." 

Tompson,  in  the  same  issue  of  the  Market  Growers' 


VEGETABLE  FORCING 


Journal,  comments  as  follows  about  the  use  of  hot  water 
in  sterilizing  soils  : 

"We  have  some  progressive  growers  who  have  done  good  work 
with  hot  water  and  are  becoming  advocates  of  this  method  when 
properly  used.  The  plan  is  to  force  the  water  into  the  soil  under 
pressure,  with  more  or  less  live  steam  combined  with  the  water.  A 
gas  pipe  about  4  feet  long  is  placed  on  the  end  of  a  hose  and  the 
pipe  is  forced  into  the  soil  to  a  depth  of  6  or  8  inches.  This  puts 
the  water  down  quite  deep  where  the  heat  is  held  and  warms  the 
soil  downward  as  well  as  upward.  This  necessitates  very  thorough 
work,  the  pipes  being  forced  into  the  soil  every  inch  or  two  back 
and  forth  across  the  beds  and  thus  thoroughly  saturating  the  soil 
with  boiling  water.  The  ground  seems  to  be  heated  to  a  depth  of 
10  or  12  inches  and  cucumber  growers  have  succeeded  in  eliminating 
trouble  from  nematodes  very  much  more  successfully  by  this  method 
than  by  any  other.  Sterilizing  for  other  common  diseases  of  let- 
tuce, cucumbers  and  tomatoes  is  easy  compared  with  nematode  de- 
struction." 


CHAPTER  VII 
INSECT  ENEMIES  AND  THEIR  CONTROL 

The  insect  problem  demands  the  most  careful  con- 
sideration of  greenhouse  vegetable  growers.  Practically 
every  greenhouse  crop  has  one  or  more  insect  enemies. 
Some  of  these  pests  are  parasites  on  the  roots,  and  others 
feed  on  parts  of  the  plant  above  ground.  They  cause 
enormous  losses  annually.  The  various  means  of  con- 
trol are  better  understood  than  they  were  a  few  years 
ago,  and  for  that  reason  future  losses  should  gradually 
diminish.  Success  in  each  instance  depends  primarily  on 
timeliness  and  thoroughness  of  application  of  the  proper 
method  of  control. 

Preventive  measures. — Cleanliness  in  the  greenhouses 
and  adjoining  workrooms  is  exceedingly  important  in 
preventing  insect  depredations.  The  entire  establish- 
ment should  have  a  thorough  cleaning  annually,  and 
more  frequently  if  possible.  The  most  propitious  time 
for  a  complete  renovation  is  during  the  summer,  usually 
in  August,  when  there  are  no  growing  crops  in  the 
houses.  It  is  then  possible  to  remove  all  rubbish,  repaint 
the  wood  work,  take  out  decayed  parts  of  benches,  and 
to  thoroughly  clean  every  part  of  the  range,  packing 
room  and  furnace  rooms. 

Not  only  should  a  thorough  cleaning  be  made  annually, 
but  rubbish  which  is  likely  to  harbor  insect  pests  should 
not  be  allowed  to  accumulate  at  any  time  under  the 
benches  or  about  the  workrooms.  Weeds  in  the  houses, 
especially  during  the  summer  months,  are  almost  certain 
to  become  the  hosts  of  pests  which  later  may  develop 
into  enemies  of  the  forcing  crops.  It  is  almost  equally 
important  to  keep  the  premises  about  the  greenhouses 

103 


104  VEGETABLE  FORCING 

free  from  weeds  and  debris  which  may  harbor  foes  of  the 
vegetables  grown  under  glass. 

Steam  sterilization  (Chapter  VI)  is  universally  ad- 
mitted to  be  the  most  effective  preventive  measure  in 
controlling  many  of  the  insect  foes  of  forcing  crops. 
Fumigation  with  hydrocyanic  gas,  at  the  rate  of  five 
ounces  of  cyanide  of  potassium  to  1,000  cubic  feet  of 
space,  is  destructive  to  all  animal  and  plant  life,  but  it 
should  not  be  used  when  there  are  any  crops  in  the 
houses. 

Care  should  be  exercised  to  select  for  greenhouse  pur- 
poses soil  which  is  free  from  white  grubs,  cutworms  and 
wireworms.  If  they  are  known  to  exist  in  the  soil,  thor- 
ough steam  sterilization  before  the  beds  are  planted  will 
be  a  certain  method  of  destroying  them.  Insect  enemies 
may  be  introduced  through  manure,  and  it  is  therefore 
important  to  apply  it  to  the  beds  before  they  are 
sterilized. 

Red  spiders  and  various  insects,  like  thrips,  aphids, 
white  fly  and  nematodes,  may  be  transferred  to  the 
houses  on  plants.  When  this  happens,  the  plants  should 
be  dipped,  fumigated  or  perhaps  destroyed,  if  they  are 
badly  infested. 

The  rotation  of  crops  is  always  helpful  in  avoiding 
losses  from  insect  depredations.  For  example,  it  is  much 
more  difficult  to  control  the  white  fly  on  tomatoes  if  the 
crop  is  grown  throughout  the  year  than  it  is  if  lettuce  is 
produced  a  part  of  the  year. 

Insect  ravages  are  generally  less  harmful  to  crops  that 
are  making  a  vigorous  growth.  It  is  important,  there- 
fore, to  employ  every  possible  means  to  promote  rapid 
growth,  avoiding  at  the  same  time  the  development  of 
soft,  tender  plant  tissues,  which  are  preferred  by  insects 
and  very  susceptible  to  the  attack  of  fungi. 

Steam  sterilization  is  extensively  used  for  the  control 


INSECT    ENEMIES    AND    THEIR    CONTROL  105 

of  insects  and  diseases  affecting  greenhouse  crops.  See 
Chapter  VI. 

Tobacco  fumigation. — It  is  undesirable  to  use  spray 
materials  as  generally  in  the  greenhouse  as  in  the 
management  of  crops  grown  out  of  doors.  It  is  possible 
to  employ  in  inclosed  structures  methods  that  are  im- 
practicable in  the  open  ground.  Fumigation  has  been 
practiced  for  many  years  in  controlling  the  ravages  of 
certain  insects,  especially  aphids  and  the  white  fly.  The 
poisonous  alkaloids  of  tobacco  are  especially  destructive 
to  the  various  species  of  aphids  or  plant  lice. 

Fumigation  by  the  burning  of  tobacco  stems  is  the 
most  common  method  of  combating  plant  lice  in  the 
large  vegetable-forcing  establshments.  The  stems, 
which  are  mostly  the  mid-veins  of  tobacco  leaves,  should 
be  as  fresh  as  possible  in  order  to  make  an  effective 
smudge.  They  can  often  be  obtained  at  slight  cost  from 
local  cigar  factories.  They  vary  considerably  in  strength, 
due  to  age  and  possibly  to  different  varieties,  and  this 
factor  should  be  kept  in  mind  when  stems  are  procured 
from  different  sources. 

The  stems  should  be  dipped  in  water  or  sprinkled,  so 
that  they  will  be  moist  when  the  smudge  is  started.  A 
convenient  way  is  to  place  the  stems  in  old  burlap  bags, 
kept  for  the  purpose,  and  to  plunge  them  into  a  tub  or 
a  tank  of  water.  After  the  surplus  water  has  been 
drained  off,  the  stems  are  ready  for  the  fire  and  the  bags 
will  be  found  convenient  for  carrying  them  through  the 
houses.  Many  greenhouse  men  simply  sprinkle  the 
stems  a  few  hours  before  they  are  wanted  for  use.  It  is 
possible  to  make  them  too  wet  to  burn,  especially  if  they 
have  been  stored  in  a  moist  place. 

Some  growers  make  the  smudge  immediately  after 
daylight,  but  the  most  common  practice  is  to  attend  to 
this  operation  in  the  evening,  when  it  will  not  interfere 
with  regular  work  in  the  houses. 


106  VEGETABLE  FORCING 

No  general  rule  can  be  given  relating  to  the  frequency 
of  fumigations.  This  will  depend  on  the  crops  under 
cultivation  and  the  prevalence  of  aphids.  It  is  important 
to  start  with  plants  apparently  free  from  lice.  If  this  is 
done,  once  a  week  may  be  sufficient.  When  there  are 
evidences  of  serious  trouble,  it  will  be  best  to  fumigate 
lightly  on  three  successive  nights.  This  is  regarded  as 
more  effective  than  one  strong  treatment,  which  may 
injure  the  plants.  If  the  three  treatments  are  successful, 
no  further  attention  may  be  needed  for  a  week  or  ten 
days. 

The  danger  of  injury  to  the  crops  will  depend  upon  the 
plants  that  are  under  cultivation;  cucumbers  are  more 
easily  affected  than  tomatoes,  but  tomatoes  are  more 
susceptible  to  injury  than  lettuce.  If  the  plants  have 
been  grown  too  rapidly  and  the  tissues  are  soft  and 
tender,  injury  is  likely  to  occur.  High  temperatures  are 
largely  responsible  for  injuries  from  tobacco  fumigation. 
Gourley  made  the  following  interesting  experiment : 

"A  small  test  was  run  on  the  effect  of  smoke  on  lettuce 
in  the  following  manner:  A  rectangular  box  32^  inches 
by  13^4  inches  by  15^4  inches  (inside  dimensions)  with  a 
capacity  of  753.6  cubic  inches  was  placed  over  four  let- 
tuce plants  of  a  size  ready  to  be  marketed.  The  tempera- 
ture within  the  box  before  starting  the  smudge  was  54 
degrees.  A  dense  smudge  was  created  in  one  end  of  the 
box  with  dried  tobacco  leaves.  When  the  box  was  raised 
after  an  exposure  of  15  minutes  the  temperature  was  115 
degrees,  and  the  plants  covered  with  a  viscid,  brownish 
precipitation  of  nicotine  compounds  which  was  intensely 
bitter  and  sickening  to  the  taste.  The  leaves  were 
mostly  limp  and  brown. 

"Again  the  box  was  placed  over  four  fresh  plants  of 
the  same  size  as  the  former ;  the  temperature  was  stand- 
ing at  60  degrees  within  the  box.  Two  sections  of  stove 
pipe  were  secured ;  the  lower  one  had  a  false  bottom  of 


INSECT   ENEMIES   AND    THEIR    CONTROL 


107 


wire  on  which  we  could  build  the  smudge  and  pass  it  up 
into  the  box  through  the  second  piece  of  pipe.  The 
dimensions  of  the  pipe  were  4  feet  long  and  7  inches  in 
diameter.  The  smoke  was  thus  cooled  somewhat  before 
it  came  in  contact  with  the  lettuce.  The  exposure  as 
before  was  15  minutes.  When  the  box  was  raised  the 
temperature  was  90  degrees,  being  15  degrees  lower  than 
in  the  previous  trial.  The  leaves  were  not  injured  nearly 
as  much,  but  in  the  same  manner,  indicating  that  the 
injury  was  proportional  to  the  amount  of  heat  accom- 
panying the  smudge.  This  injury  occurs  rarely  in 
practice." 

A  practical  grower  has  observed  that  lettuce  is  easily 
injured  by  tobacco  fumigation  at  a  temperature  of  60 
degrees,  that  light  treat- 
ments may  be  made  at  55  de- 
grees without  injury,  that 
strong  fumigations  may  oc- 
cur at  50  degrees  without 
injury,  and  that  it  is  almost 
impossible  to  damage  the 
crop  at  a  temperature  of  45 
degrees. 

The  danger  of  injury  will 
be  very  much  less  if  the 
plants  are  dry  during  the 
smudging.  It  is  necessary, 
of  course,  to  have  the  house 
well  filled  with  the  smudge 
in  order  to  make  the  treat- 
ment fully  efficacious. 

The  stems  are  sometimes 
placed  on  the  walks,  but  it 
is  better  to  put  them  in 

kettles,    Cans,    wire    Cages    Or  Fig.  34.— Garbage  can  suspended  to 

other  metal  utensils.     Some     Jjjjo  stems. in  fumigating  with  t0' 


108  VEGETABLE   FORCING 

of  the  Toledo  growers  use  a  special  wire  cage  in  which 
the  dry  stems  are  placed  and  then  soaked  with  water. 
Garbage  cans  (Fig.  34)  are  employed  sometimes. 

The  fires  are  always  started  in  the  lower  part  of  the 
house,  as  on  the  walks,  because  the  smudge  rises  slowly 
and  gradually  fills  the  house.  The  stems  create  a  con- 
siderable degree  of  heat  and,  therefore,  the  fires  should 
not  be  started  close  to  wood  or  other  inflammable  ma- 
terial. One  fire  for  each  50-foot  unit  of  house  25  by  40 
feet  wide  will  give  satisfactory  results.  A  little  experi- 
ence will  soon  enable  the  operator  to  use  the  required 
amount  of  stems  to  make  a  good  smudge.  Some  dry 
material,  such  as  paper,  small  pieces  of  wood,  corn  cobs, 
etc,  are  placed  in  the  bottom  of  the  container,  and  the 
moist  tobacco  stems  above.  A  common  practice  is  to  use 
a  little  kerosene  to  start  the  fires. 

Tobacco  preparations  in  various  proprietary  forms  may 
be  purchased  from  nurserymen,  seedsmen  and  other 
dealers.  Most  of  them  are  excellent  and  some  are  con- 
sidered more  efficacious  than  the  burning  of  tobacco 
stems.  They  are  also  more  convenient  to  use  and  the 
expense  may  be  no  greater,  especially  if  the  stems  must 
be  bought  from  a  middleman  instead  of  a  factory,  and 
shipped,  perhaps,  a  long  distance,  thus  incurring  a  heavy 
freight  bill. 

Fumigating  powders  are  in  common  use.  These  may 
be  placed  on  shallow  pans  in  the  greenhouse  walks,  and 
a  few  drops  of  kerosene  added  to  facilitate  ignition.  The 
powders  burn  slowly  and  gradually  fill  the  house  with 
fumes  which  are  poisonous  to  all  forms  of  aphids. 

Liquid  extracts  of  tobacco  are  popular  among  florists, 
and  they  are  used  to  some  extent  by  vegetable  growers. 
These  concentrated  forms  may  be  vaporized  by  pouring 
them  on  hot  pipes,  plunging  hot  irons  into  kettles  of  the 
extracts,  or  by  the  use  of  hot  steam  admitted  through  a 
steam  hose  into  the  extract.  Special  vaporizing  lamps 


INSECT    ENEMIES    AND    THEIR    CONTROL  109 

may  be  purchased  which  are  highly  satisfactory.  The 
liquid  extracts  may  also  be  diluted  and  applied  as  a  spray. 
This  plan  is  not  regarded  as  satisfactory  for  lettuce,  be- 
cause it  is  not  desirable  for  any  kind  of  a  tobacco  solution 
to  come  into  contact  with  the  leaves. 

Sheets  of  paper,  impregnated  with  concentrated 
tobacco  extracts,  are  popular  with  some  gardeners,  and 
especially  with  frame  vegetable  growers.  The  papers  are 
easily  ignited  and  convenient  to  use. 

Ordinary  tobacco  powder  is  often  dusted  on  cucumber 
plants  and  sometimes  on  lettuce,  but  it  is  only  moder- 
ately effective,  because  it  serves  mainly  as  a  repellent. 
It  also  acts  as  a  preventive  when  placed  on  top  of  the 
soil  when  the  lettuce  is  planted. 

Hydrocyanic  gas  fumigation. — This  method  of  destroy- 
ing insects  which  feed  on  greenhouse  vegetable  crops  is 
now  employed  by  most  of  the  large  commercial  growers. 
It  made  slow  progress  for  many  years,  mainly  for  two 
reasons — the  danger  to  the  fumigator  and  to  others  likely 
to  be  about  the  establishment,  and  the  possibility  of 
injuring  the  plants. 

Numerous  experiments,  however,  made  by  scientists  as 
well  as  by  practical  growers,  have  demonstrated  that 
hydrocyanic  gas,  when  properly  used,  is  a  cheap,  safe  and 
effective  fumigant.  By  its  use  insects  may  be  destroyed 
which  are  extremely  difficult  to  exterminate  by  any  other 
method.  Among  such  pests  is  the  white  fly,  a  most 
serious  enemy  of  greenhouse  tomatoes  and  cucumbers. 
This  gas  is  a  deadly  poison  also  to  thrips,  plant  lice  and 
mealy  bugs,  but  it  does  not  kill  the  red  spider  or  scale 
insects  unless  used  sufficiently  strong  to  kill  the  plants. 

The  equipment  needed  for  fumigation  with  hydro- 
cyanic gas  is  stone  or  earthenware  jars  or  crocks,  which 
should  be  of  gallon  size  and  fairly  narrow.  Wrapping 
paper  or  preferably  small  paper  bags  will  be  needed  for 
the  crystals  of  cyanide  of  potassium  or  cyanide  of  sodium, 


110  VEGETABLE  FORCING 

which  should  be  98  to  99  per  cent  pure.  Ordinary  com- 
mercial sulphuric  acid  will  be  needed  to  produce  the  gas, 
and  a  glass  or  porcelain  measure  or  dipper  should  be  pro- 
vided to  handle  the  sulphuric  acid.  Metal  dippers  are 
quickly  destroyed  by  this  acid.  A  suitable  basket  will  be 
required  to  carry  the  packages  of  cyanide  through  the 
greenhouses. 

Numerous  experiments  have  been  made  to  determine 
the  amount  of  cyanide  of  potassium  which  will  prove 
effective  in  destroying  the  white  fly  and  yet  cause  no 
injury  to  the  plants.  So  many  factors  are  involved  that 
no  general  rule  can  be  given.  Much  depends  on  the  con- 
dition of  the  houses.  Poorly  constructed  and  old  houses 
with  many  small  openings  between  the  panes  of  glass 
and  wooden  parts  will  require  more  cyanide  than  new, 
tightly  built  ranges.  Young,  tender  plants  are  much 
more  easily  injured  than  older  plants  with  tougher 
tissues.  If  it  is  necessary  to  fumigate  on  a  windy  night 
much  of  the  gas  will  escape.  Again,  if  the  plants  are 
wet  or  if  the  humidity  of  the  house  is  very  high  the  plants 
will  be  susceptible  to  injury. 

The  earlier  writers  on  this  subject  advocated  one  ounce 
of  cyanide  of  potassium  to  5,000  cubic  feet  of  space. 
Later,  when  fumigators  became  more  skillful,  one  ounce 
to  3,000  cubic  feet  was  often  employed.  More  recently 
some  of  the  most  extensive  and  successful  growers  find 
that  when  proper  conditions  exist  the  plants  are  not  in- 
jured if  an  ounce  of  cyanide  is  used  to  1,000  cubic  feet. 
This  amount,  however,  is  probably  the  maximum  quan- 
tity which  should  be  used  under  the  most  favorable  con- 
ditions. Some  of  the  most  cautious  growers  prefer  to 
make  lighter  treatments  of  one  ounce  to  2,000  to  2,500 
cubic  feet,  and  to  fumigate  more  frequently.  Ordinarily, 
the  treatment  should  be  repeated  at  intervals  of  ten  days 
until  no  insects  can  be  found.  As  a  preventive  measure 
some  greenhouse  men  fumigate  at  intervals  of  two  weeks, 


INSECT    ENEMIES   AND    THEIR    CONTROL  111 

regardless  of  whether  insects  can  be  found  or  not.  For 
those  who  have  not  had  experience  in  this  method  of 
fumigating,  it  will  be  safer  for  them  to  begin  with  light 
treatments,  note  results  and  increase  the  amount  of 
cyanide  if  necessary  and  also  the  frequency  of  the  appli- 
cations. Five  ounces  of  cyanide  to  1,000  cubic  feet  may 
be  used  when  there  are  no  crops  in  the  houses  and  it  is 
desired  to  kill  red  spiders  and  all  other  animal  life. 

Daylight  fumigations  have  not  been  successful.  It  is 
always  important  to  attend  to  this  operation  at  night, 
when  there  is  no  wind.  The  workmen,  too,  are  then  out 
of  the  houses  and  visitors  are  not  likely  to  be  in  the 
establishment. 

Dry  plants  and  low  humidity  are  exceedingly  impor- 
tant in  order  to  avoid  injury  to  the  crops.  The  losses 
sustained  by  those  who  first  tried  cyanide  fumigation 
were  often  due  to  excessive  moisture  conditions.  Any 
accumulation  of  moisture  on  the  plants  is  certain  to 
absorb  the  gas  and  thus  damage  the  plants,  and  high 
humidity  causes  the  gas  to  settle  quickly  to  the  beds  and 
walks.  There  should  be  no  watering  or  spraying  on  the 
days  when  the  houses  are  to  be  fumigated. 

There  is  some  difference  of  opinion  regarding  the 
effect  of  the  gas  at  different  temperatures  of  the  green- 
houses, though  most  growers  believe  that  the  plants  are 
more  susceptible  to  injury  when  the  temperature  is  high. 
There  is  probably  little  if  any  difference  in  the  effect  of 
the  gas  at  temperatures  ranging  from  50  to  60  degrees. 

Trials  made  in  a  tomato  house  at  The  Pennsylvania 
State  College  indicate  that  tobacco  and  cyanide  fumiga- 
tions may  be  made  to  advantage  at  the  same  time.  Pans 
of  tobacco  powders  were  ignited  and  immediately  there- 
after the  bags  of  cyanide,  at  the  rate  of  only  one-third  of 
an  ounce  to  each  1,000  cubic  feet  of  space,  were  placed  in 
the  crocks.  This  double  treatment  was  found  to  be 
highly  satisfactory  in  combating  the  white  fly.  It  is  be- 


112  VEGETABLE  FORCING 

lieved  that  the  tobacco  fumes  serve  to  disturb  and  dis- 
lodge the  flies,  and  that  the  hydrocyanic  gas  is  then  more 
effective  in  killing  them. 

There  should  be  sufficient  acid  to  react  with  all  of  the 
cyanide  crystals,  and  sufficient  water  to  dissolve  the 
potassium  acid  sulphate  which  results  from  the  reaction. 
A  common  formula  is  one  ounce  of  cyanide  of  potassium, 
two  ounces  of  sulphuric  acid  and  four  ounces  of  water. 
A  more  recent  formula,  which  is  wholly  satisfactory  and 
less  expensive,  is  1-1-3,  which  provides  sufficient  acid  for 
chemical  reaction.  Sodium  cyanide,  apparently,  is  just 
as  effective  as  potassium  cyanide.  When  this  is  used  the 
formula  should  be  3-4-6.  Sodium  cyanide  will  produce 
more  gas,  and  only  three-fourths  as  much  is  required  per 
1,000  cubic  feet  as  when  potassium  cyanide  is  used. 

The  jars  are  usually  placed  20  to  30  feet  apart  in  the 
central  walk  of  the  greenhouse.  Their  distance  apart 
depends  on  the  width  of  the  houses.  A  successful  grower 
of  cucumbers  uses  12  jars  in  a  25  by  300  foot  house.  He 
places  six  ounces  of  water,  six  ounces  of  sulphuric  acid 
and  1^2  ounces  of  cyanide  of  potassium  in  each  jar.  A 
good  plan  is  to  have  three  jars  for  a  house  20  by  100  feet 
in  size,  four  jars  for  a  house  25  by  100  feet  and  five  jars 
for  a  house  30  by  100  feet  in  size.  In  very  wide  houses 
or  in  ridge  and  furrow  ranges  there  may  be  a  number  of 
rows  of  crocks  or  vessels. 

Preparations  for  the  use  of  hydrocyanic  gas  are  made 
before  dark.  The  ventilators  and  all  openings  of  the 
house  are  closed  as  tightly  as  possible.  The  valves  regu- 
lating the  heating  pipes  are  adjusted  so  that  they  will 
require  no  further  attention  until  morning.  Care  is 
exercised  to  keep  all  workmen,  visitors,  children  and 
animals  out  of  the  houses.  The  jars  are  then  properly 
distributed  along  the  walks,  and  water  is  placed  in  them. 
The  sulphuric  acid  is  added  about  half  an  hour  before  the 
cyanide  is  to  be  used.  Violent  heat  is  caused  by  the 


INSECT    ENEMIES    AND    THEIR    CONTROL 


113 


chemical  reaction  of  the  sulphuric  acid  and  water  and  it 
is  important  for  the  liquid  to  cool  considerably  before  the 
cyanide  is  added  in  order  to  prevent  too  rapid  generation 
of  the  gas. 

Some  growers  drop  the  cyanide  into  jars  without  the 
use  of  paper  bags  or  packages.  It  is  much  safer,  how- 
ever, to  use  paper  containers,  for  these  will  resist  the 
action  of  the  acid  for  a  few  seconds  and  make  it  a  safer 
operation  for  the  fumigator.  The  proper  amounts  of 
cyanide  may  be  weighed  on  suitable  scales  or  it  may  be 
more  convenient  to  have  them  prepared  in  proper 
amounts  by  the  druggist. 

When  everything  is  in  readiness,  all  doors  are  closed 
and  locked  except  the  ones  through  which  the  operator  is 
to  pass.  If  there  are  several  rows  of  crocks  there  must 
be  a  man  for  each  row.  The 
packages  are  carried  in  a  basket 
or  a  convenient  receptacle,  and 
the  operator  usually  starts  at  the 
end  of  the  house  farthest  from 
the  packing  or  service  rooms.  He 
passes  rapidly  from  vessel  to  ves- 
sel, carefully  placing  a  packet  in 
each  crock  so  as  to  avoid  splash- 
ing the  contents  or  breathing  the 
gas  that  might  escape  before  he 
proceeds  to  the  next  crock.  After 
the  last  crock  is  passed,  he  leaves 
the  house  and  locks  the  door 
which  has  been  left  open  for  his 
exit.  The  house  should  be  care- 
fully guarded  for  a  few  hours. 
There  is  absolutely  no  danger  in 
this  operation  if  proper  care  is  ex- 


Fig.  35. — Female  nematode 
(Heterodera  radicicola)  mag- 
nified 85  diameters:  a, 
mouth;  b,  spherical  sucking 
bulb;  c,  ovaries  as  seen 
through  the  body  wall;  d, 


's    generally    not    difficult   to 

P,  ...  isolate     them     in     water    by 

Some     growers     prefer    tO     raise     breaking  open  the  galls  con- 


the   ventilation   in   two   or  three 


them'   (After  N'  A' 


114 


VEGETABLE  FORCING 


hours  after  fumigation  is  begun,  but  the  more  com- 
mon practice  is  to  wait  until  the  next  morning.  The 
houses  may  then  be  entered  for  a  few  minutes  with 
safety  and  the  ventilators  opened  as  wide  as  the  weather 
will  permit.  It  is  better  not  to  stay 
in  the  houses  until  the  ventilators  have 
been  opened  for  at  least  one-half  hour. 
The  odor  of  the  gas  will  be  noticeable 
the  next  morning,  but  this  need  cause 
no  concern. 

Sulphuric  acid  should  also  be  handled 
with  care.  It  is  destructive  to  clothing 
and  it  burns  the  flesh.  Flesh  burns 
should  immediately  be  washed  with 
water,  and  oil  or  vaseline  applied. 

Inasmuch  as  cyanide  of  potassium  is 
a  most  dangerous  poison,  it  should  be 
kept  under  lock  and  key,  away  from 
children.  The  smallest  granule  taken 
internally  will  be  almost  certain  to 
cause  death. 

It  is  a  simple  matter  to  determine 
the  number  of  cubic  feet  in  a  green- 
house. For  instance,  suppose  the 
house  is  even  span  and  30  by  100  feet 
in  size,  6  feet  from  ground  to  eaves  and 
9  feet  from  eaves  to  ridge.  The  cubic 
contents  below  the  eaves  would  be  30 
by  6  by  100  or  18,000  cubic  feet.  The 
space  above  the  eaves  would  be  30  by 
9  by  100  divided  by  two,  or  13,500  cubic 
feet,  a  total  of  31,500  cubic  feet  for  the 
house.  To  determine  the  space  above 

spear;    /,    intestine;   gt       the     eaVCS     in     ™     Uneven-Span     hoUSC, 

blind  ends  of  testicles;  draw  a  perpendicular  line  from  the 
ridge  to  the  level  of  the  eaves,  thus 
making  two  triangles.  The  contents 


Fig.  3fi. — Male  nem- 
atode:  I,  worm  in  pro- 
file view;  II,  head  of 
the  same,  more  highly 
magnified;  III,  middle 
region  of  worm  show- 
ing blind  ends  of  the 
sexual  organs;  IV,  pos- 
terior extremity.  The 
drawings  were  prepared 
from  stained  speci- 
mens, examined  in  car- 
bolic acid  solution. 
a,  lips;  b,  oesophageal 
tube;  c,  median  bulb; 
d,  excretory  pore;  e, 


h,  testicles;  i,  specula; 
/,  rudimentary  bursa; 
k,  anus.  (After  N.  A. 
Cobb.) 


INSECT    ENEMIES    AND    THEIR    CONTROL 


115 


of  each  triangle  may  be  ascertained  by  multiplying  the  height 
of  the  perpendicular  side  of  the  triangle  by  the  length  of  the 
base  line  and  that  product  by  the  length  of  the  house.  This 
total  divided  by  two  will  give  the  capacity  of  the  triangle.  If 
the  eaves  are  not  on  a  level,  the  space  may  be  divided  into 
rectangles  and  triangles  and  the  cubic  contents  of  the  house 
calculated  similarly  to  the  foregoing  method. 

Miscellaneous  insecticides,  in  addition  to  those  pre- 
viously described  in  this  chapter,  are  sometimes  em- 
ployed in  the  treatment  of  greenhouse  vegetable  crops. 
Kerosene  emulsion  is  a 
standard  spray  for  the 
control  of  aphids, 
though  the  liquid  to- 
bacco preparations  are 
generally  preferred  for 
use  in  the  greenhouse. 
Arsenate  of  lead,  when 
an  arsenical  poison  is 
needed,  is  most  satis- 
factory for  greenhouse 
purposes.  Various 
soaps  and  soap  prep- 
arations, some  of  them 
proprietary,  are  useful 
in  checking  the  ravages 
of  certain  insect  pests. 
It  will  seldom  be  nec- 

however    tO  Use 


Fi£»  37.  —  Galls   on   cucumber   roots  produced 
.  by  nematodes. 

any  of  these  materials 

if  the  major  treatments  previously  described  are  thorough 

and  timely. 

The  spraying  apparatus  for  greenhouse  use  should  be 
light  and  convenient  to  operate.  The  various  forms  of 
knapsack  sprayers  are  sometimes  employed.  Automatic 
tank  pressure  sprayers  are  becoming  popular.  Some 
growers  prefer  bucket  pumps,  but  they  are  not  the  most 


116 


VEGETABLE  FORCING 


convenient  forms  for  greenhouse  sprayers.  Hand 
atomizers  are  very  useful  for  treating  small  lots  of  plants. 
An  extensive  Ohio  grower  uses  a  pressure  tank  mounted 
on  a  cart.  A  very  long  half-inch  hose  enables  him  to 
spray  the  houses  with  only  an  occasional  moving  of  the 
cart.  The  plan  is  entirely  satisfactory. 

Nematodes  (Heterodera  radicicola). — These  little 
pests,  which  are  nearly  microscopic  in  size,  are  variously 
known  as  gall  worms,  eelworms  and  thread  worms.  The 
trouble  which  they  cause  is  often  referred  to  as  root  knot 
and  root  gall,  and  sometimes  as  big  root.  The  last  term 
should  not  be  confused  with  the  malady  "big  root"  and 
"club  root"  of  cabbage  and  other  brassica,  caused  by  a 
slime  mold.  Nematodes  are  widely  distributed  through- 
out the  temperate  and  tropical  parts  of  the  world.  High 
temperatures  and  long  summer  seasons  are  most  favor- 
able for  their  existence,  and  for  these  reasons  they  arc 
most  troublesome  in  southern  sections. 

Greenhouse  conditions  are  naturally  ideal  for  nema- 

todes.  They  are  es- 
pecially destructive  to 
the  cucumber  and  to- 
mato, and  they  some- 
times infest  asparagus, 
muskmelon,  pea,  bean, 
beet,  celery,  carrot, 
eggplant,  pepper,  on- 
ion, spinach  and  radish. 
More  than  500  kinds  of 
plants  are  said  to  be 
subject  to  the  attack  of 
nematodes.  Roots  with 
soft,  tender  tissues, 
such  as  the  cucumber, 

Fig.  38.— Roots  of  tomato  plant  completely      provide    favorable    COn- 

8a"  worms'    (After  Ge°rge  F'     ditions  for  this  enemy. 


INSECT    ENEMIES    AND    THEIR    CONTROL  117 

The  two  sexes  of  the  nematode  are  shown  in  Figs.  35 
and  36.  These  worms  are  so  minute  that  it  is  necessary 
to  use  enlarged  illustrations  in  order  to  show  their 
various  features.  Fig.  35  represents  the  mature  female, 
which  is  nearly  pear-shaped  and  less  than  a  millimeter  in 
length.  The  body  cavity  of  the  female  is  occupied  by 
eggs  and  larvae.  Fig.  36  shows  the  slender,  threadlike 
male,  which  is  1  to  1.5  millimeters  in  length,  with  en- 
larged parts.  Scofield,  of  the  U.  S.  Department  of  Agri- 
culture, gives  the  following  life  history  of  the  nematode 
in  Circular  91,  U.  S.  Bureau  of  Plant  Industry : 

"The  larvae  of  the  gall  worm  upon  hatching  from  the  egg,  which 
hatching  sometimes  occurs  within  the  body  of  the  parent,  ultimately 
escape  from  the  host  plant  and  live  for  a  period  in  the  surrounding 
soil.  These  larvae,  although  very  active,  have  but  little  power  of 
progressive  locomotion,  and  the  spread  of  infection  from  place  to 
place  must  depend  upon  the  transportation  of  infested  soil  or  in- 
fested plants.  Soon  after  emerging  from  the  parent  and  the  tissue 
of  the  host  plant  these  larvae  seek  other  roots  and  bore  their  way 
into  the  plant  tissues  by  means  of  a  spearlike  structure,  which  is 
protruded  from  the  mouth.  They  feed  upon  the  cell  sap  of  the  host 
plants. 

•'After  fertilization  takes  place  the  females  begin  reproduction 
by  forming  eggs  within  the  body.  These  eggs  are  laid  at  the  rate 
of  from  10  to  15  a  day,  and  it  is  estimated  that  one  female  may  lay 
as  many  as  500  eggs.  After  completing  the  egg-laying  process  the 
female  dies,  the  male  having  died  soon  after  fertilizing  the  female. 

"The  worm  lives  from  one  season  to  the  next,  either  in  the  egg 
stage  or  in  the  larval  stage  within  the  host  plant.  The  life  of  the 
individual  worm  is  short  (only  a  few  weeks),  when  temperature 
and  moisture  conditions  are  such  as  to  favor  growth.*  It  is  pos- 
sible, therefore,  to  greatly  reduce  the  numbers,  if  not  to  exterminate 
the  worm  entirely,  by  keeping  the  infested  land  free  from  plants 
upon  which  the  worm  can  feed." 

The  characteristic  root  galls  of  the  cucumber,  pro- 
duced by  this  parasite  are  shown  in  Fig.  37,  of  the 

*  Additional  information  concerning  the  life  history  of  this  parasite,  with 
a  list  of  susceptible  plants  and  details  of  experiments  in  controlling  the  nematode 
in  the  southeastern  United  States,  may  be  found  in  Bulletin  217  of  the  Bureau  of 
Plant  Industry,  entitled  "Root-Knot  and  Its  Contrpl,"  by  Dr.  Ernest  A.  Bessey. 


118 


VEGETABLE  FORCING 


tomato  in  Fig.  38,  of  lettuce  in  Fig.  39.  Serious  derangement 
of  the  normal  life  functions  is  caused  by  the  worms,  which 
results  in  the  development  of  irregular  galls  and  the  im- 
perfect nutrition  of  the  plant.  Evidence  of  infested  roots 
may  be  indicated  by  the  leaves  becoming  sickly  or 
yellowish  or  by  the  stunted  and  dwarfed  appearance  of 
the  entire  plant.  If  the  attack  is  serious,  yields  will  be 

, ,    greatly     diminished     or     the 

plants  may  die  before  any 
crop  is  harvested.  The  fleshy 
enlargements  are  watery  and 
tender,  and  they  provide 
ready  entrance  for  fungi  and 
bacteria,  which  may  cause 
rapid  decay  and  additional  in- 
terference with  the  nutrition 
of  the  host  plant. 

Nematodes  migrate  very 
slowly,  not  more  than  a  few 
feet  a  year,  but  they  may  be 
introduced  or  distributed  in 
the  greenhouse  by  means  of 
infested  soil,  manure  and 
plants.  They  may  be  con- 
veyed about  the  establishment 
on  the  shoes  of  the  workmen 
and  on  the  various  tools 


Fig.  39.— Galls     on     lettuce    roots        which  are   Used   for  tillage   Op- 
caused    by    nematodes. 

erations. 

Numerous  preventive  measures  have  been  advocated. 
Chemicals  of  various  kinds  have  not  proved  practical. 
Lime  is  probably  of  no  value,  for  the  worms  will  live  for 
several  days  in  a  saturated  solution  of  lime.  Formalin 
has  been  used  with  slight  success.  Freezing,  desiccation 
and  inundation  are  valuable  to  some  extent,  but  they  are 
not  regarded  favorably  by  greenhouse  growers.  The 


INSECT    ENEMIES    AND    THEIR    CONTROL 


119 


only  means  which  have  been  found  to  be  economical  and 
satisfactory  in  destroying  the  pests  are  thorough  steriliza- 
tion with  steam  and  hot  water.  (See  Chapter  VI.)  After 
the  beds  have  been  planted  and  the  crop  is  found  to  be 
infested,  nothing  can  be  done  until  the  plants  are  removed 
and  the  soil  sterilized. 

Aphis. — Various  species  of  the  aphis  feed  on  the  differ- 
ent vegetable  forcing  crops.  They  are  commonly  called 
plant  lice  and  green  and  black  flies.  While  there  is  con- 
siderable variation  in  the  structure  of  the  different  species 
as  well  as  in  their  life  histories,  all  have  sucking  mouth 


Fig.  40. — White  fly  (Aleyrodes  vaporariorum) ;  a,  egg;  &,  young  larva;  c,  pupa,  top 
view;  d,  pupa,  side  view;  e,  adult — c,  d,  e,  about  25  times  natural  size;  a,  b,  still 
more  enlarged;  (a — d,  after  Morrill,  Tech.  Bui.,  Mass.  Exp.  Sta.;  e,  original.) 

parts.  They  are  extremely  persistent  on  some  crops, 
such,  for  example,  as  the  green  fly  on  lettuce.  The 
young  are  brought  forth  alive,  and  they  reach  maturity 
in  seven  to  ten  days  and  begin  to  produce  young,  so  that 
innumerable  insects  may  appear  from  a  few  parents 
within  a  remarkably  short  time,  unless  preventive 
measures  are  taken. 


120  VEGETABLE  FORCING 

Inasmuch  as  plant  lice  have  sucking  instead  of  biting 
mouth  parts,  they  cannot  be  killed  by  stomach  poisons 
such  as  arsenate  of  lead,  but  must  be  destroyed  by  con- 
tact insecticides  or  by  suffocating  fumigants.  Tobacco 
extract  and  soap  solutions  are  the  most  commonly 
applied  of  the  liquids,  and  tobacco  fumigation  is  uni- 
versally regarded  as  the  most  desirable  means  of  con- 
trolling the  green  fly,  especially  on  lettuce.  See  page  224. 

White  fly  (Aleyrodes  vaporariorum). — The  green- 
house white  fly  is  widely  distributed  among  establish- 
ments devoted  to  vegetable  forcing.  It  is  universally 
regarded  as  one  of  the  worst  foes  of  greenhouse  crops, 
and  must  be  combated  in  an  intelligent  and  vigorous 
manner  in  order  to  prevent  the  most  serious  ravages. 
Tomatoes  and  cucumbers  suffer  most  from  the  depreda- 
tions of  the  white  fly.  Lettuce,  eggplant,  bean,  melon 
and  many  floral  crops  are  subject  to  attack. 

A  complete  description  and  life  history  of  the  white 
fly  (Fig.  40),  and  remarks  on  the  appearance  of  infested 
plants  are  given  as  follows  in  Circular  57,  U.  S.  Bureau 
of  Entomology: 

"The  mature  white  flies  of  both  sexes  are  four-winged  insects 
scarcely  more  than  l^  millimeters  or  three-fiftieths  of  an  inch  in 
length.  The  adult  white  flies,  as  well  as  the  scalelike  larvae,  are 
provided  with  sucking  mouth  parts.  In  a  short  time  after  the 
emergence  of  the  adult  from  the  pupa  case,  the  body,  legs  and  wings 
become  covered  with  a  white,  waxy  substance  which  gives  this,  as 
well  as  other  species  of  the  genus,  a  characteristic  floury  appearance. 
The  adults  feed  nearly  continuously  during  their  existence.  If  de- 
prived of  food,  they  will  rarely  live  for  a  longer  period  than  three 
days  under  ordinary  temperature  conditions.  The  longest  recorded 
length  of  life  of  one  of  these  insects  in  the  adult  condition  is  36 
days,  but  it  seems  probable  that  the  average  length  of  adult  life  is 
much  greater  than  this  would  indicate.  The  largest  number  of  eggs 
which  an  adult  white  fly  is  positively  known  to  have  deposited  is 
129,  but  this  number  is  probably  below  the  average.  Indeed,  the 
specimen  which  produced  this  number  of  eggs  with  little  doubt  de- 
posited over  50  others  which  were  not  recorded.  The  number  of 


INSECT    ENEMIES    AND    THEIR    CONTROL  121 

eggs  deposited  per  day  by  an  adult  female  white  fly  in  a  laboratory 
has  been  found  to  average  very  nearly  four.  Probably  in  the  warmer 
temperature  of  a  greenhouse  this  number  is  greater  by  one  or  two 
eggs  per  day.  These  observations,  even  though  falling  short  of 
showing  the  normal  increase  in  numbers  of  this  species,  emphasize 
the  importance  of  a  remedy  which  will,  above  all,  destroy  the  adults 
and  check  at  once  the  rapid  deposition  of  eggs.  A  peculiarity  of 
the  egg-laying  habits  of  this  and  some  other  species  of  white  fly  is 
the  tendency  to  deposit  the  eggs  in  a  circle  while  feeding,  using  the 
beak  as  a  pivot.  These  circles,  when  completed,  are  about  \l/2  mm. 
in  diameter  and  usually  contain  from  10  to  20  eggs  each.  On  the 
more  hairy  leaves  groups  of  eggs  of  this  kind  are  less  frequently 
met  with  than  on  those  which  are  more  nearly  smooth.  The  ma- 
jority of  the  adults  are  found  upon  the  upper  and  newer  leaves  of 
the  food  plant.  They  are  almost  invariably  found  upon  the  under- 
side of  the  leaves,  and  it  is  here  that  nearly  all  the  eggs  are  de- 
posited, although  many  are  found  upon  the  tender  stems  and  leaf 
petioles  and  a  very  few  scattering  ones  on  the  upper  surfaces  of 
the  leaves. 

"The  eggs  are  distinguishable  with  difficulty  by  the  naked  eye, 
being  but  one-fifth  of  a  millimeter,  or  one  one  hundred  and  twenty- 
fifth  of  an  inch,  in  length.  They  are  more  or  less  ovoid  in  form 
and  suspended  from  the  leaf  by  a  short,  slender  stalk.  With  ordinary 
greenhouse  temperatures  the  eggs  hatch  in  from  10  to  12  days.  The 
newly  hatched  insect  is  flat,  oval  in  outline,  and  provided  with  ac- 
tive legs  and  antennae.  It  rarely  crawls  farther  than  one-half  inch 
from  the  empty  eggshell  before  settling  down  and  inserting  into  the 
tissue  of  the  leaf  its  threadlike  beak.  After  feeding  for  five  or  six 
clays,  the  insect  is  ready  to  molt  its  skin.  The  second  and  third 
stages  are  much  alike,  except  in  size,  and  differ  principally  from  the 
first  stage  in  that  the  legs  and  antennae  are  vestigial  and  apparently 
functionless.  These  two  stages  occupy  from  four  to  six  days  each. 

"The  so-called  pupal  stage,  up  to  the  time  when  growth  ceases, 
is  in  reality  the  fourth  larval  stage,  the  fourth  larval  skin  envelop- 
ing the  true  pupa.  The  pupae  and  empty  pupa  skins  are  quite  con- 
spicuous when  the  insects  are  abundant.  Their  outline  is  similar 
to  that  of  the  larvae,  but  they  are  thicker  and  boxlike,  about  three- 
fourths  of  a  millimeter,  or  three  hundredths  of  an  inch  in  length, 
and  provided  with  long,  slender  wax  rods  or  secretions  which  are 


122  VEGETABLE  FORCING 

useful  in  distinguishing  this  from  nearly  allied  species  of  the 
white  fly. 

"The  entire  stage  from  the  insect's  third  molt  to  the  emergence 
of  the  adult  form  lasts  from  12  to  16  days  in  the  laboratory  and 
greenhouse.  The  adult  emerges  from  a  T-like  opening,  leaving  the 
glistening  white  pupa  case  attached  to  the  leaf.  At  first  the.  wings 
of  the  adult  are  crumpled  close  to  the  body,  giving  them  a  peculiar 
appearance.  In  the  course  of  a  few  hours  the  wings  unfold  and  the 
insect  has  then  completed  its  development,  which  has  extended  over 
nearly  five  weeks,  if  under  the  ordinary  temperature  conditions  of 
a  greenhouse. 

"Appearance  of  infested  plants. — As  already  stated,  the  upper 
leaves  of  a  plant  are  preferred  by  the  adult  females  for  the  deposi- 
tion of  their  eggs.  Thus  there  is  a  slow  but  continuous  migration 
of  adults  upward  to  keep  pace  with  the  unfolding  of  the  leaf  buds. 
On  thoroughly  infested  plants  we  find  on  the  uppermost  leaves  only 
adults  and  freshlv  laid  eggs;  a  little  lower  on  the  plants  we  find 
eggs  in  the  process  of  hatching;  and,  finally  on  the  lowermost  parts 
of  the  plants  we  find  discolored,  shriveled  leaves  with  many  pupae 
and  emerging  adults  and  few,  if  any,  unhatched  eggs  or  young 
larvae.  The  larvae  and  pupae  secrete  little  globules  of  honey-dew, 
so  named  after  the  material  of  a  like  nature  secreted  by  plant  lice. 
These  globules  usually  either  drop  or  are  forcibly  ejected,  and  fall- 
ing on  the  upper  surface  of  leaves  directly  below,  give  them  a 
glazed  appearance.  This  is  frequently  followed  by  the  growth  of  a 
sooty  fungus  which  hastens  the  complete  destruction  of  the  leaf. 

"When  overcrowding  of  the  young  occurs,  this  fungous  growth 
finds  favorable  conditions  for  its  development  on  the  under  surface 
of  the  leaf,  resulting  in  the  destruction  of  many  of  the  immature 
insects.  Owing  to  the  interference  with  the  respiratory  processes 
of  the  leaf,  both  by  the  bodies  of  the  insects  themselves  and  by  the 
fungous  growths  due  to  them,  badly  infested  plants  have  a  tendency 
to  wilt  when  exposed  to  the  sun's  rays.  In  seriously  infested  green- 
houses the  leaves  of  the  plants  gradually  die,  the  lower  leaves  first, 
and  if  unchecked  the  insects  greatly  impair  the  value  and  vitality 
of  the  plants,  even  though  they  do  not  actually  cause  their  total 
destruction." 

In  the  control  of  the  white  fly  in  greenhouses,  preven- 
tive measures  should  be  taken  as  much  as  possible.  The 
pests  are  so  minute  that  they  may  easily  be  introduced 


INSECT   ENEMIES   AND    THEIR   CONTROL  123 

into  a  house  without  being  observed  until  considerable 
damage  has  been  caused.  When  plants  are  transferred 
from  frames  or  other  houses  they  should  be  in  inspected 
with  extreme  care,  and  if  even  a  few  white  flies  are  found 
the  plants  should  be  fumigated  before  they  are  set  in  the 
permanent  beds.  Special  boxes  or  small  beds  may  be 
employed  for.this  purpose,  where  hydrocyanic  gas  may 
be  used  with  safety.  Fumigation  with  this  gas  is  recog- 
nized as  the  most  effective  means  of  controlling  the  white 
fly  on  tomatoes  and  cucumbers.  See  Page  109  for  di- 
rections. 

Nicotine  solutions  are  applied  to  some  extent  to  kill 
the  white  fly.  These  sprays  are  not  effective  unless  they 
come  in  contact  with  the  insects.  The  same  may  be  said 
of  various  soap  solutions.  Fumigation  involves  much  less 
labor  and  it  is  not  so  expensive  as  spraying,  whatever 
may  be  the  character  of  the  solution. 

Red  spider  (Tetranychus  telarius,  Linn.)  is  a  common 
pest  of  the  greenhouse  cucumber  and  tomato,  and  it  also 
feeds  on  the  melon,  bean,  eggplant  and  many  ornamental 
plants  which  are  grown  under  glass.  If  unchecked  in  its 
ravages  serious  losses  may  result. 

Though  commonly  known  as  the  red  spider,  it  is  a 
mite  instead  of  a  true  spider,  and  for  this  reason  Ewing  of 
the  Oregon  Agricultural  College  has  suggested  the  name 
"spider  mite."  The  fact  that  the  body  is  seldom  red  is 
an  additional  reason  for  dropping  the  old  name.  Ewing 
has  made  a  very  thorough  study  of  the  spider  mite,  and 
we  are  indebted  to  him  for  most  of  the  information  which 
is  given  here  in  regard  to  its  life  history.  Those  who  are 
especially  interested  in  the  spider  mite  should  read  Bul- 
letin 121  of  the  Oregon  Agricultural  College. 

According  to  Ewing  and  other  workers,  a  single  female 
may  deposit  from  51  to  94  eggs,  and  she  may  lay  as  many 
as  15  in  a  day.  If  a  mite  is  feeding  on  soft,  tender  parts 
of  favored  host  plants,  and  the  temperature  is  high,  the 
greatest  number  of  eggs  will  be  laid.  In  other  words, 


124  VEGETABLE  FORCING 

low  temperature  and  poor  food  are  unfavorable  to  egg 
production,  and  suitable  conditions  maintained  in  the 
greenhouse  for  plants  requiring  high  temperatures  are 
favorable  for  the  rapid  multiplication  of  this  pest.  The 
incubation  period  ranges  from  three  to  eight  days,  the 
length  depending  on  temperature.  All  of  the  eggs  noted 
by  Ewing  hatched,  unless  the  temperature  was  too  low 
or  they  were  destroyed  by  predaceous  insects.  The 
spider  mite  is  parthenogenetic ;  that  is,  fertilization  is 
not  necessary  in  order  that  the  eggs  may  hatch. 

The  new  almost  flesh-colored  larva  begins  to  feed  soon 
after  it  is  hatched,  and  remains  near  the  plant  where  it 
emerged  from  the  shell.  While  the  larva  does  not  spin 
a  web  it  is  frequently  found  on  webs  spun  by  adults.  A 
trifle  more  than  three  days  is  the  average  period  of  the 
larva  stage,  and  about  the  same  time  is  required  to  pass 
the  first  nymph  stage,  when  the  mites  are  also  active 
feeders.  The  second  nymphs  have  the  ability  to  spin 
webs,  and  the  duration  of  this  period  is  practically  the 
same  as  for  the  first  stage.  There  is  an  active  and  a 
quiescent  period  in  each  of  the  three  stages  explained. 
The  average  duration  of  the  adult  stage  is  over  21  days, 
and  eggs  are  laid  throughout  the  period,  except  about  the 
first  five  days. 

The  eggs  are  nearly  spherical,  covered  with  a  tough 
shell,  pearly  in  appearance  and  0.09  millimeter  in  size. 
They  are  deposited  singly,  but  generally  close  together. 
The  larva  is  almost  spherical,  flesh-colored  and  has  but 
six  legs.  It  averages  0.19  millimeter  in  length.  The 
first  nymph  is  very  similar  to  the  larva,  except  that  it 
possesses  an  extra  pair  of  legs  and  is  larger,  being  0.27 
millimeter  in  length.  The  second  nymph  is  very  similiar 
in  shape  to  the  first,  but  averages  0.36  millimeter  in 
length. 

The  adults  vary  greatly  in  color.  They  may  be  green, 
yellowish,  greenish  yellow  or  bright  orange.  Females 
average  0.42  millimeter  in  length  and  the  males  0.32 


INSECT    ENEMIES   AND    THEIR    CONTROL  125 

millimeter  in  length.  The  mite  is  provided  with  suc- 
torial mouth  parts,  requiring  for  its  extermination  contact 
insecticides  rather  than  stomach  poisons. 

Numerous  measures  are  recommended  for  the  control 
of  spider  mites  in  greenhouses.  The  destruction  of  all 
weeds  in  the  greenhouse  during  the  summer  season  is  a 
valuable  precaution.  Weeds  near  the  houses  may  also  be 
a  source  of  infestation.  Plants  which  are  purchased  or 
transferred  to  other  houses  should  be  carefully  examined, 
and  sprayed  if  found  to  be  infested.  Infested  individual 
plants  may  be  found  from  time  to  time.  Such  plants 
should  receive  prompt  attention,  to  prevent  the  distribu- 
tion of  the  pests.  Plants  should  be  promptly  removed 
from  the  houses  after  crops  have  been  harvested,  so  as 
to  prevent  further  breeding  of  the  mites.  Rotation  of 
crops  is  always  helpful  in  controlling  the  ravages  of  the 
red  spider.  Fumigation  with  tobacco  and  ordinary 
strengths  of  hydrocyanic  gas  is  not  effective,  because  the 
mite,  not  being  a  true  insect,  does  not  possess  spiracles  or 
breathing  spores,  hence  killing  by  suffocation  is  ex- 
tremely difficult.  An  experiment  was  made  by  Ewing, 
in  which  he  used  approximately  one  ounce  of  potassium 
cyanide  to  1,000  cubic  feet  of  space ;  50  larvae,  40  nymphs 
and  30  adults  were  placed  on  plants,  and  results  noted. 
The  ventilators  were  not  raised  for  15  hours.  At  the  end 
of  this  period,  32  larvae,  25  nymphs  and  27  adults  were 
found  to  be  alive,  thus  proving  the  inefficiency  of  this 
gas  in  killing  spider  mites. 

Various  sprays  are  used  successfully  in  combating  this 
enemy  of  greenhouse  crops.  Water  has  long  been  known 
as  an  enemy  of  the  red  spider,  though  the  use  of  water 
alone  does  not  always  prove  fully  effective.  There  are 
abundant  evidences  that  the  force  of  the  spray,  whether 
of  water  or  some  other  solution,  is  an  important  factor  in 
destroying  mites.  A  fine  spray  applied  with  force  knocks 
the  mites  from  the  leaves,  thus  injuring  them  so  that  few 


126  VEGETABLE  FORCING 

return.    Special  nozzles  have  been  devised  for  this  purpose. 

Soap  solutions  are  often  employed,  but  there  is  a  dif- 
ference of  opinion  regarding  their  value.  One  ounce  of 
laundry  soap  to  five  gallons  of  water  is  an  approved 
formula  for  this  purpose.  Whale  oil  soap,  two  pounds  to 
50  gallons  of  water,  is  also  used. 

Sulphur  in  various  forms  is  used  extensively  in  com- 
bating red  spiders.  Dry  sulphur  may  be  applied  to  the 
plants  with  a  dust  gun.  Sulphur  as  a  liquid  spray  has  not 
been  very  effective  against  the  red  spider  on  cucumbers. 
Sulphur  is  sometimes  painted  on  hot  greenhouse  pipes, 
where  it  slowly  volatilizes,  thus  becoming  a  fumigant. 
For  many  years  florists  considered  this  practice  of  value 
in  suppressing  red  spiders.  Experiments  made  by  Ewing 
show  the  futility  of  it.  He  says:  "Eleven  days  of  this 
treatment  had  not  the  slightest  effect  upon  the  spider 
mites.  The  practice  may  be  considered  as  foolish  and  use- 
less as  the  equally  old  and  time-honored  custom  of  throw- 
ing handfuls  of  powdered  sulphur  in  the  crotches  of  trees 
in  order  to  eradicate  mites  in  an  orchard." 

Tobacco  sprays  are  employed  by  many  greenhouse 
growers.  The  Ohio  Experiment  Station  obtained  excel- 
lent results  in  the  greenhouse  by  using  one-half  pint  of 
a  proprietary  tobacco  extract,  two  quarts  of  lime  sulphur 
and  25  gallons  of  water. 

Oil  emulsions  are  effective  sprays  against  the  red 
spider.  Ewing  recommends  two  gallons  of  distillate,  four 
pounds  of  whale  oil  soap  and  100  gallons  of  water.  Dis- 
solve the  soap  in  a  few  gallons  of  hot  water  by  heating. 
Add  the  oil  and  agitate  in  the  usual  way  with  a  force 
pump  until  the  solution  is  well  emulsified,  and  then  dilute 
to  100  gallons. 

Miscellaneous  pests,  such  as  white  ants,  white  grubs, 
sow  bugs,  snails,  millipedes,  wireworms  and  cutworms, 
which  may  cause  injury  to  greenhouse  vegetable  crops, 
may  be  eradicated  by  thorough  soil  steam  sterilization 
before  the  crops  are  started  in  the  permanent  beds. 


CHAPTER  VIII 
DISEASES  AND   THEIR  CONTROL 

An  important  factor. — Anyone  who  engages  in  vege- 
table forcing  will  be  compelled  to  give  consideration  to 
the  disease  factor.  If  a  new  house  is  constructed  and  the 
utmost  care  exercised  in  the  selection  of  soil  and  in  the 
management  of  the  crops,  diseases  may  not  appear  for 
several  years.  But  they  will  ultimately  be  found  and  if 
not  checked  they  will  soon  cause  serious  losses. 

If  the  grower  is  to  cope  with  the  disease  factor  in  a 
satisfactory  manner,  he  should  be  familiar  with  the  para- 
sites which  are  most  likely  to  appear.  He  should  know 
their  life  histories  and  how  the  crops  become  infected. 
A  knowledge  of  the  conditions,  which  are  most  favorable 
to  the  development  and  dissemination  of  the  diseases  is 
highly  important.  The  several  means  of  prevention  and 
control  should  be  studied  and  the  utmost  care  exercised 
in  the  selection  and  execution  of  the  plans  which  are 
most  promising.  In  many  instances  success  depends 
more  upon  timeliness  and  thoroughness  than  upon  any 
particular  plan. 

Sanitation. — All  that  has  been  said  in  Chapter  VII  per- 
taining to  greenhouse  sanitation,  and  its  importance  in 
avoiding  insect  depredations,  applies  even  more  directly 
to  the  disease  problem.  The  utmost  cleanliness  at  all 
times  in  and  about  the  greenhouses  and  service  rooms 
will  be  valuable  as  a  preventive  measure.  The  use  of  dis- 
infectants during  the  summer  or  at  other  times  when 
there  are  no  crops  in  the  beds  will  prove  effective  in 
guarding  against  possible  attacks.  There  are  times  when 
it  pays  to  disinfect  pots,  flats,  dibbers  and  all  soil  tillage 
tools  used  in  the  beds.  Refuse  and  all  old  plants  should 
be  promptly  removed  after  the  harvesting  of  every  crop, 

127 


128  VEGETABLE  FORCING 

so  as  to  immediately  stop  the  further  progress  of  any 
disease  that  may  be  present. 

Soil  selection. — Unless  the  most  thorough  steam  sterili- 
zation is  practiced,  too  much  care  cannot  be  exercised  in 
the  selection  of  soil  which  is  not  infected  with  disease 
germs  of  the  crops  to  be  grown.  For  example,  it  will  be 
folly  to  select  a  garden  soil  in  which  lettuce,  tomatoes 
and  cucumbers  have  been  grown  for  many  years  when 
these  same  crops  are  to  be  grown  under  glass.  When 
new  ranges  are  constructed,  it  may  be  possible  to  select 
soils  so  free  from  infection  that  radical  measures  of  con- 
trol, such  as  steam  sterilization,  may  not  be  necessary 
for  several  years. 

Manure  selection. — Infection  of  greenhouse  vegetable 
crops  may  easily  occur  through  stable  manures.  For 
this  reason,  soil  sterilization,  whether  steam  or  formalin, 
is  used,  should  be  practiced  after  the  manure  is  applied. 

Infected  plants. — Diseases  are  often  introduced  when 
infected  plants  are  purchased  or  transferred  from  other 
houses.  In  new  establishments,  where  there  may  be  no 
evidence  of  fungous  or  bacterial  troubles  of  any  kind,  it 
is  highly  undesirable  to  take  chances  in  buying  plants 
from  any  district,  even  under  the  assurance  that  infection 
does  not  exist  on  the  premises  of  the  grower  who  offers 
the  plants  for  sale. 

Influence  of  light. — Practically  no  experiments  have 
been  made  upon  the  influence  of  light  in  relation  to  the 
development  of  parasitic  fungi.  It  has  been  observed 
that  shading  or  the  reduction  of  light  hinders  the  progress 
of  certain  diseases  of  plants  grown  in  the  open.  For  ex- 
ample, Duggar  calls  attention  to  the  fact  that  ginseng 
growers  have  found  that  lath  screens  are  valuable  in 
preventing  sun  scald  on  the  margin  of  the  leaves,  and, 
inasmuch  as  a  serious  blight  is  supposed  to  gain  entrance 
through  the  tissues  thus  affected,  shading  actually  di- 
minishes the  infection  from  this  disease.  It  is  possible 
that  shading  is  sometimes  beneficial  in  the  control  of 


DISEASES   AND   THEIR   CONTROL  129 

parasitic  fungi  of  greenhouse  vegetable  crops,  though  the 
opposite  view  is  universally  held  by  successful  growers. 

Various  diseases  of  greenhouse  cucumbers  and  toma- 
toes are  much  more  troublesome  during  the  fall  and  win- 
ter months  than  during  the  spring  and  early  summer. 
The  success  of  the  spring  crops  is  attributed  almost 
wholly  to  more  light  and  more  sunshine.  The  days  are 
longer,  and  there  is  a  larger  proportion  of  bright,  sunny 
weather  to  cloudy  days  than  there  is  from  November  to 
March.  This  fact  should  be  fully  considered  when  mak- 
ing cropping  plans.  Some  crops,  such  as  lettuce,  do  bet- 
ter with  the  minimum  amount  of  light  than  other  crops 
like  the  tomato  and  cucumber.  For  this  reason  lettuce  is 
most  generally  grown  as  a  fall  crop  in  preference  to  cu- 
cumbers and  tomatoes.  And  this  decision,  too,  is  usually 
based  on  the  fact  that  cucumbers  and  tomatoes  are  far 
more  susceptible  to  disease  during  the  fall  and  winter 
than  from  March  1  to  August  1.  Sunlight  not  only  favors 
the  most  rapid  growth  of  plants,  but  it  also  prevents  the 
germination  of  certain  disease  spores.  Shading,  however, 
has  a  place  in  greenhouse  management.  The  subject  is 
discussed  on  page  36. 

The  influence  of  moisture. — Excessive  watering  in  the 
greenhouse  invariably  results  in  soft,  tender  plant  tissues 
which  permit  the  easy  entrance  and  rapid  development 
of  parasitic  diseases. 

The  constant  maintenance  of  high  humidity  in  the 
greenhouses  is  just  as  dangerous  as  an  excessive  amount 
of  moisture  in  the  soil.  It  also  encourages  the  growth  of 
succulent  tissues  and  is  most  favorable  to  the  production 
and  germination  of  spores.  Growers  who  do  not  ventilate 
the  houses  freely  and  regularly,  to  reduce  humidity  as 
well  as  temperatures,  are  almost  certain  to  experience 
heavy  losses  from  the  attacks  of  various  diseases. 

While  constant  high  humidity  in  the  houses  should  be 
avoided,  it  is  thought  by  some  that  moisture  on  the  leaves 
is  an  advantage  when  bordeaux  mixture  is  to  be  used. 


130  VEGETABLE  FORCING 

In  this  connection  it  is  stated,  in  the  Market  Growers' 
Journal,  that  by  merely  watering  bed  surfaces  with  a  hose, 
little  moisture  reaches  the  foliage,  and  thus  the  bordeaux 
mixture  does  not  become  effective.  To  the  writer  the 
explanation  lies  in  the*  need  of  atmospheric  moisture  to 
make  the  copper  compounds  soluble  in  bordeaux  mixture. 
Wherever,  therefore,  there  is  in  greenhouse  practice  no 
moistening  of  the  foliage,  bordeaux  mixture  will  not 
become  available  for  fungicidal  effect  to  any  considerable 
extent. 

It  is  important,  therefore,  to  maintain  a  supply  of  soil 
moisture  sufficient  to  cause  normal  growth.  It  also  seems 
that  inadequate  soil  moisture,  which  may  cause  a  slow, 
weak  growth,  makes  the  plant  more  susceptible  to  cer- 
tain diseases. 

The  influence  of  temperature. — Very  high  temperature 
in  the  greenhouse  may  render  the  plants  susceptible  to 
disease.  No  harm  will  result  from  high  temperature  if 
there  is  sunshine,  normal  soil  moisture  conditions  and 
proper  ventilation.  But  excessive  heat  and  high  humidity 
in  the  absence  of  sunshine  are  certain  to  cause  very  rapid 
growth  and  soft,  tender  tissues  which  are  most  sensitive 
to  diseases.  High  temperatures  and  abundant  moisture 
also  provide  the  most  favorable  conditions  for  the  germi- 
nation of  spores  and  the  further  progress  of  diseases. 
Great  extremes  in  temperature  should  be  avoided  because 
they  are  not  conducive  to  the  strongest  growth  of  the 
plant. 

Vigor  of  growth. — It  is  universally  conceded  that 
greenhouse  plants  which  are  making  a  normal,  vigorous 
growth  are  the  least  susceptible  to  disease.  It  behooves 
the  grower,  then,  to  maintain  soil  and  atmospheric  condi- 
tions which  are  most  favorable  to  the  plants  under  culti- 
vation. This  involves  careful  and  intelligent  fertilizing, 
watering  and  ventilating.  There  must  be  no  neglect  in 
firing  the  boilers  or  in  any  other  operation  that  is  essential 
to  the  growth  of  disease-resistant  plants. 


DISEASES   AND   THEIR   CONTROL  131 

Crop  rotation  is  an  important  means  of  avoiding 
troublesome  diseases  of  vegetable  forcing  crops.  If  a 
three  or  more  crop  system  of  rotation  can  be  adopted, 
the  chances  of  serious  losses  from  diseases  are  much  less 
than  if  but  one  crop  is  grown. 

Resistant  varieties  or  strains. — Some  progress  has  been 
made  in  the  development  of  varieties  and  strains  of  vege- 
tables for  outdoor  culture  which  are  largely  resistant  to 
diseases.  Very  little  progress,  however,  has  been  made  in 
this  direction  with  vegetables  which  are  profitable  for 
forcing  purposes.  There  is  no  reason  why  strains  or  even 
varieties  should  not  be  found  or  produced  which  would 
be  highly  or  quite  resistant  to  fungous  and  bacterial  in- 
fections. 

Steam  sterilization. — This  is  one  of  the  most  im- 
portant means  of  preventing  numerous  fungous  diseases 
of  greenhouse  crops.  See  Chapter  VI. 

Formalin  sterilization  is  effective  as  a  preventive  meas- 
ure, where  it  is  impracticable  to  use  steam.  See  Chapter 
VI  and  page  98. 

Summer  mulch. — It  has  been  found  that  mulches  of 
manure  or  other  vegetable  matter,  applied  during  the 
summer  and  watered  often  enough  to  keep  the  soil  moist, 
are  effective  in  destroying  disease  germs  of  greenhouse 
forcing  crops.  See  page  78. 

Spraying  to  control  diseases  affecting  greenhouse  vege- 
tables is  just  as  unpopular  as  spraying  to  check  the  rav- 
ages of  insect  pests.  It  is  a  slow,  tedious  operation,  that 
should  be  avoided  if  possible.  But  however  thorough  has 
been  the  work  of  sterilization  and  fumigation,  and  the 
observance  of  the  various  precautions  previously  dis- 
cussed, the  grower  sometimes  finds  it  an  advantage  to 
employ  fungicidal  sprays.  Their  effectiveness  depends 
upon  the  selection  of  the  proper  mixture  for  each  dis- 
ease and  applications  that  will  be  both  timely  and 
thorough. 

Bordeaux    mixture    is    unquestionably    the    most    im- 


132  VEGETABLE  FORCING 

portant  fungicide  for  the  treatment  of  vegetables  grown 
under  glass.  The  chief  objection  to  its  use  is  the  dis- 
coloration of  the  fruits  or  products,  and  this  is  a  serious 
objection  if  the  mixture  is  applied  to  the  crops  a  short 
time  before  they  are  to  be  marketed.  The  strength  of  the 
proportions  of  the  mixture  may  vary  from  two  pounds  of 
copper  sulphate  and,  two  pounds  of  stone  lime  to  50  gal- 
lons of  water,  to  five  pounds  of  copper  sulphate  and  five 
pounds  of  stone  lime  to  50  gallons  of  water.  Ordinarily, 
plants  like  the  cucumber  and  tomato  are  not  injured  if 
the  5-5-50  formula  is  employed. 

Various  directions  are  given  for  making  bordeaux  mix- 
ture, but  a  simple  plan  is  to  dissolve  the  copper  sulphate 
in  a  few  gallons  of  hot  water  in  a  wooden  pail.  Slowly 
slake  the  lime  in  another  vessel  and  add  enough  water 
to  make  a  thick  milk  solution.  The  dissolved  copper  sul- 
phate is  then  poured  into  the  barrel  or  tank  containing 
about  40  gallons  of  water,  the  lime  milk  added  and  the 
solution  stirred.  Additional  water  may  be  used  if  nec- 
essary to  make  the  total  volume  50  gallons.  Separate  stock 
solutions  of  copper  sulphate  and  of  lime  milk  may  be 
kept  on  hand,  but  the  prepared  mixture  deteriorates  when 
left  standing.  It  is  important  that  unslaked  stone  lime 
rather  than  air-slaked  lime  be  employed.  Air-slaking 
may  be  prevented  by  keeping  the  stone  lime  in  tightly 
covered  vessels.  The  Ohio  Station  reports  that  bordeaux 
mixture  is  most  effective  when  the  atmosphere  of  the 
house  is  so  highly  humid  that  the  leaf  surfaces  are  moist. 

Ammoniacal  copper  carbonate. — As  previously  indi- 
cated, bordeaux  mixture  leaves  a  deposit  on  the  plants 
and  fruits  which  is  objectionable  if  the  products  are  soon 
to  be  marketed.  For  this  reason,  some  growers  prefer  to 
use  ammoniacal  copper  carbonate — which  leaves  only  a 
slight  deposit — previous  to  harvesting  and  marketing 
certain  crops,  though  this  fungicide  is  not  so  effective  as 
bordeaux  mixture.  The  mixture  contains  the  following 
constituents : 


DISEASES    AND    THEIR    CONTROL  133 

Copper  carbonate 5  ounces 

Ammonia  (26°   Baume)   3  pints 

Water _ 50  gallons 

Dilute  the  ammonia  with  water  to  about  five  times  its 
volume.  Make  a  thin  paste  of  the  copper  carbonate  with 
a  small  quantity  of  water,  and  add  this  to  the  ammonia 
by  constant  stirring.  After  diluting  to  50  gallons  of 
water  the  mixture  is  ready  for  application.  It  should  be 
used  as  promptly  as  possible  because  the  ammonia 
evaporates  rapidly. 

Potassium  sulphide  or  liver  of  sulphur  is  sometimes 
employed  in  the  greenhouse,  especially  when  it  is  desir- 
able to  avoid  the  discoloration  of  the  foliage.  From 
three  to  five  ounces  of  potassium  sulphide  is  used  to  10 
gallons  of  water. 

Sulphur  is  sometimes  applied  as  a  dust  over  the  plants 
for  the  treatment  of  mildews. 


CHAPTER  IX 
STARTING  PLANTS 

Plants  of  high  quality  are  essential  to  success  in  the 
production  of  any  greenhouse  crop.  Profits  are  often 
diminished  because  inferior  plants  are  used  in  setting  the 
beds.  They  should  be  of  the  proper  size,  not  too  large 
nor  too  small,  and  ready  for  the  beds  the  very  day.  any 
space  becomes  vacant.  They  should  be  strong,  stocky 
and  vigorous  rather  than  weak,  spindling  and  succulent. 
The  color  of  the  leaves  should  be  dark  green  rather  than 
pale  green.  It  is  especially  important  that  they  have  a 
well-developed  root  system.  The  management  of  the 
young  plants  should  be  so  skillful  that  there  will  be  no 
evidence  of  diseases  and  insects  when  they  are  transferred 
to  the  permanent  beds. 


Fig.  41. — Two   nurseries   in    a    four-acre   Boston    range, 
different  sizes. 


Note   lettuce   seedlings   of 


Seed  of  high  quality. — Failures  are  often  due  to  poor 
seed.     The  greenhouse  grower,  who  usually  makes  suc- 


134 


STARTING  PLANTS 


135 


cessive  sowings  at  short  intervals,  is  not  likely  to  be  dis* 
appointed  in  the  seed  not  germinating.  This  matter, 
however,  should  not  be  overlooked.  Germination  tests, 
made  in  advance  of  the  usual  dates  for  sowing,  may  be 
the  means  of  avoiding  loss  and  disappointment.  Very 
little  time  is  required  to  make  such  tests,  and  the  results 
may  much  more  than  compensate  for  the  slight  expense. 

The  term  "high  quality"  as  applied  to  seeds  has  a  much 
broader  meaning  than  the  mere  matter  of  germination. 
It  relates  primarily  to  the  quality  of  the  crop  produced 
from  tne  seed  selected  and  planted.  Unfortunately,  many 
greenhouse  men  do  not  seem  to  fully  appreciate  the  value 
of  high-grade  seeds.  They  fail  to  grasp  the  fact  that 
planting  the  best  seed  may  materially  increase  their 
profits.  Chances  are  taken,  year  after  year,  in  using  seed 
of  unknown  quality,  until  they  discover,  accidentally, 
perhaps,  that  the  superior  quality  of  the  produce  sold  by 
their  competitors  is  largely  due  to  the  planting  of  better 
seed. 

We  should  bear  in  mind  that  greenhouse  space  is 
precious,  that  the  area  with  its  glass  roof  and  artificial 
heat  is  worth  many  times  an  area  of  equal  size  in  the 
open.  It  is  folly  ever  to  use  seed  that  we  do  not  know 
will  produce  satisfactory  crops. 


Fig.  42. — Nursery   in   large   range   near  Boston.     Head  lettuce   plants. 


136  VEGETABLE  FORCING 

High-quality  seed  for  greenhouse  purposes  may  be  ob- 
tained by  two  methods.  The  usual  one  is  to  purchase  the 
seed  from  reputable  dealers.  If  this  plan  is  followed,  it 
is  important  for  each  grower  to  make  small  plantings  in 
order  to  determine  the  merits  of  the  seed  in  producing  a 
satisfactory  crop,  and  in  meeting  definite  market 
conditions. 

It  is  gratifying  to  note  in  this  connection  that  a  fairly 
large  number  of  seedsmen  specialize  more  or  less  in  the 
development  of  strains  of  vegetables  adapted  to  green- 
house culture.  This  is  the  ideal  system  and  with  the 
growth  of  the  vegetable-forcing  industry  it  will  become 
more  attractive  to  commercial  seed  growers. 

It  is  interesting  to  observe,  however,  that  nearly  all  of 
the  extensive  and  the  most  successful  growers  of  green- 
house vegetables  breed  their  own  seed.  This  statement 
does  not  apply  to  lettuce  growers,  though  some  of  them 
save  their  own  seed,  but  it  does  to  the  men  who  are  pro- 
ducing cucumbers  and  tomatoes  under  glass.  These 
master  growers  claim  that  the  practice  enables  them  to 
make  larger  profits  because  of  the  superiority  of  their 
products. 


Fig.  43. — Flat  of  Grand  Rapids  lettuce  seedlings. 

When  seed  is  saved  from  home-grown  plants  a  few 
principles  should  be  carefully  observed.  In  the  first 
place,  no  progress  whatever  will  be  made  if  fine  speci- 
mens are  selected  from  the  picking  baskets.  It  is  not 


STARTING  PLANTS  137 

unusual  for  a  small,  weak  plant  to  produce  an  extra  fine 
tomato,  cucumber,  pepper  or  eggplant.  Not  individual 
specimens,  but  the  plant  must  be  regarded  as  the  unit  of 
selection. 

To  begin  with,  the  grower  should  have  a  very  definite 
idea  of  what  he  wants.  The  market  demands  should  also 
be  known  before  a  given  type  is  decided  upon.  After  a 
definite  conclusion  is  reached  concerning  the  most  desir- 
able size,  shape,  color  and  quality  of  the  product  to  be 
grown,  the  most  careful  observation  is  made  when  the 
crops  are  harvested.  Here  and  there  will  be  found  plants 
which  approach  the  ideals  of  the  grower,  and  they  are 
also  vigorous,  productive  and  perhaps  free  from  disease. 
Such  plants  are  marked  and  the  seed  saved  in  separate 
packages.  The  packets  are  then  numbered  and  small 
plantings  of  each  made  for  the  next  crop.  It  will  be 
found  that  some  of  the  selections  do  not  perpetuate  their 
good  qualities,  while  others  do.  Selections  are  again 


Fig.  44. — Flat  of  lettuce  plants  ready  for  transplanting  into  the  beds. 

made  from  the  best  plants  of  the  best  lots,  and  in  the 
course  of  a  few  generations  a  strain  of  special  merit 
should  be  developed  if  the  work  has  been  done  intelli- 
gently. Some  of  the  leading  greenhouse  growers  are 
developing  a  trade  for  special  strains,  though  this  is 
seldom,  if  ever,  their  motive  in  breeding  better  seeds. 

Separate  plant  houses  (Figs.  41  and  42),  are  almost  in- 
dispensable   in    large    establishments.      They    make    it 


138  VEGETABLE  FORCING 

possible  to  maintain  temperatures  which  are  most  suit- 
able for  the  various  classes  of  plants  at  different  stages  of 
growth  without  interfering  with  the  crops  in  the  main 
houses. 

It  is  well  known  that  the  temperature  for  lettuce  imme- 
diately after  the  first  transplanting  should  average  5  to 
10  degrees  higher  than  that  for  lettuce  which  is  approach- 
ing maturity.  It  is  impossible  to  provide  the  proper 
temperature  for  both  lots  of  plants  if  they  are  in  the  same 
house.  Again,  the  main  houses  may  be  filled  with  a 
winter  crop  of  lettuce  when  it  is  time  to  start  tomatoes 
or  cucumbers  for  spring  planting.  While  it  is  possible, 
with  skillful  management,  to  accomplish  this,  it  is  not  a 
simple  undertaking. 

The  humidity  of  the  houses  can  also  be  better  regu- 
lated if  there  are  separate  nurseries  for  starting  the  plants. 
Fumigation,  too,  may  be  necessary  in  the  plant  compart- 
ment when  not  in  the  main  houses,  or  vice  versa.  If 
separate  houses  are  provided  growth  may  be  forced  or  re- 
tarded, as  may  be  required  to  prepare  the  plants  for  the 
beds  at  the  proper  time.  The  advantages  of  separate 
plant  houses  are  apparent. 


Fig.  45. — Lettuce  plants  in  flats. 


STARTING  PLANTS 


139 


The  nursery  should  be  conveniently  located  with  refer- 
ence to  the  various  units  of  the  entire  range  of  houses. 
Numerous  valves  should  be  placed  in  the  heating  pipes  so 
that  the  most  exact  regulation  of  temperature  will  be 
possible.  Not  less  than  two  compartments,  and  prefer- 
ably three  or  four,  should  be  provided  for  large  ranges  of 
houses.  Level,  water-tight  beds  or  benches  for  the  sub- 
irrigation  of  plants  in  fiats  will  be  found  an  advantage, 
especially  if  the  soil  is  silty  or  clayey  and  inclined  to  bake. 

Flats  vs.  beds. — While  many  greenhouse  men  prefer  to 
start  and  grow  their  plants  in  beds  (Figs.  41  and  42) 
there  are  special  advantages  in  using  flats.  (Figs.  43,  44 
and  45.)  If  solid  ground  beds  are  employed  it  is  a  tire- 
some task  to  bend  for  hours  over  them  sowing  and 
covering  the  seed. 

Plant  boxes  may  be  placed  on  tables  of  convenient 
height  and  the  sowing  done  in  greater  comfort.     The 
same  statement  may  be  made  in  regard  to  the  first  trans 
planting  of  the  seedlings.     High  stools  may  be  used,  if 
desired,  when  the  work  of  sowing  and  transplanting  is 


Fig.  46. — Utilizing  shelf  space  in  an  overcrowded  house, 
the  beds  underneath. 


Unfair  to  the  plants  in 


done  at  tables,  and  the  tables  may  be  shifted  as  desired  in 
the  potting  room  or  greenhouses. 


140  VEGETABLE  FORCING 

Flats  are  a  great  convenience  in  shifting  the  plants 
about  the  premises  and  in  utilizing  space.  (Fig.  46.) 
They  may  be  easily  carried  or  carted  here  and  there,  to 
provide  the  best  conditions  for  growth,  or  to  supply 
young  plants  to  the  workmen  as  they  transplant  into  the 
permanent  beds.  It  is  possible  to  control  soil  moisture 
conditions  more  perfectly  in  flats  than  in  beds,  which  is 
a  most  important  factor  in  growing  good  plants. 

Finally,  plants  grown  in  flats,  especially  if  an  inch  of 
rotten  manure  has  been  placed  in  the  bottom  of  the  boxes 
before  they  are  filled,  may  be  shifted  and  transplanted 
with  more  soil  adhering  to  the  roots  than  is  usually 
possible  with  bed-grown  plants. 

Flats  should  be  made  in  such  dimensions  that  they  may 
be  placed  on  beds  or  benches  without  the  loss  of  any 
space.  Their  exact  depth  does  not  seem  to  be  of  special 
importance.  It  has  been  demonstrated  that  just  as  good 


Fig.  47. — Flat  with  wire-mesh  bottom. 

plants  can  be  grown  in  boxes  only  2  inches  deep  as  in 
those  of  twice  that  depth.  Deep  boxes  require  more  soil 
and  they  are  heavier  to  handle.  It  is  more  difficult,  too, 
to  remove  plants  from  them  with  a  large  quantity  of  soil 
adhering  to  the  roots.  Perhaps  the  only  important  ad- 
vantage in  favor  of  deep  flats  is  that  they  do  not 
require  such  close  attention  in  watering  as  do  boxes 
that  are  only  2  inches  deep.  Some  growers  use 


STARTING   PLANTS 


141 


flats  with  bottoms  made  of  wire  netting,  as  seen  in  Fig.  47. 

Use  of  pots. — Both  earthen  and  paper  pots  are  used  in 
vegetable-forcing  establishments.  Although  they  add  to 
the  operating  expenses  by  requiring  a  larger  investment 
of  capital,  and  transplanting  cannot  be  done  so  rapidly 
from  pots  as  from  flats  and  beds,  their  advantages  are  so 
obvious  that  the  subject  deserves  special  consideration. 

The  greatest  advantage  in  using  pots  is  that  there  is 
absolutely  no  check  in  growth  when  the  plants  are  shifted 
from  pot  to  pot,  or  from  the  pots  to  the  beds  where  the 
crop  is  to  mature.  With  each  shift  there  is  no  root  dis- 
turbance of  any  kind,  and  the  additional  soil  provided  at 
each  transplanting  makes  possible  the  continuous  growth 
of  the  plant.  Uninterrupted  growth  is  particularly  im- 
portant for  plants  like  the  cucumber,  tomato,  pepper  and 


, 


Fig.  48. — Cucumber  plants  growing  in  pots  and  in  an  adjacent  bed. 

eggplant.  Again,  some  plants,  like  the  cucumber,  do  not 
transplant  so  readily  as  others.  In  such  instances,  pots 
are  practically  indispensable. 

Sometimes  it  is  impossible  to  make  the  final  shift  to 
the  beds  at  the  time  decided  upon  when  the  seed  was 
sown.  There  may  be  lack  of  sunshine  or  other  inter- 


142  VEGETABLE  FORCING 

ferences  to  retard  the  growth  of  the  plants  in  the  per- 
manent beds.  Then,  too,  market  demands  are  variable, 
and  it  becomes  necessary  at  times  to  defer  harvesting  for 
a  week  or  more  after  the  time  when  the  grower  thought 
the  beds  would  be  cleared  ready  for  another  lot  of  plants. 

If  the  plants  are  growing  in  pots,  they  may  be  held  for 
a  longer  period  than  is  possible  when  they  are  in  flats  or 
beds,  because  the  pots  are  easily  separated,  more  space 
being  thus  allowed  for  each  plant.  The  crowding  of  the 
tops  of  plants  is  much  more  injurious  than  restriction  of 
the  root  growth. 

If  separate  compartments  (Fig.  48)  are  available,  the 
potted  plants  may  be  placed  by  themselves  and  cultural 
conditions  provided  which  will  retard  their  growth. 
Even  if  the  plants  should  become  larger  than  is  desired, 
they  can  be  shifted  to  the  beds  without  difficulty,  and  a 
satisfactory  crop  may  be  obtained. 

Pots  enable  the  grower  to  utilize  every  square  foot  of 
space  in  the  greenhouse.  (See  Fig.  49.)  If  a  plant  here 
and  there  dies,  or  fails  to  make  satisfactory  growth,  the 
pot  can  be  removed  and  the  vacancy  filled  with  a  good 
plant.  It  is  also  possible  to  place  them  in  different  parts 
of  the  house,  wherever  there  may  be  unused  space.  Many 
growers  find  that  it  is  economy  to  stand  or  plunge  potted 
vegetables  for  short  periods  between  plants  in  the  per- 
manent beds,  thus  making  the  space  do  double  duty. 

If  insects  or  diseases  appear  at  any  time,  the  potted 
plants  may  be  removed  and  sprayed,  fumigated  or  per- 
haps destroyed. 

Most  greenhouse  growers  prefer  to  use  earthen  pots. 
With  good  care  they  will  last  for  many  years.  Additions 
to  the  supply  may  be  made  from  year  to  year  until  the 
required  number  has  been  purchased.  Paper  pots  of 
various  descriptions  appeal  to  others,  largely  because 
they  are  less  expensive  than  earthen  pots.  Berry  baskets 


144 


VEGETABLE  FORCING 


of  quart  size  are  used  by  some  growers  for  the  starting  of 
tomato  and  cucumber  plants.  Sometimes  the  plants  are 
not  removed  from  the  baskets,  but  the  plant  is  left  intact 
and  thus  basket  and  all  are  set  in  the  bed. 

Soil  selection  and  preparation. — Any  soil  which  is 
properly  prepared  for  use  in  the  permanent  beds  will  be 
satisfactory  for  starting  the  plants.  It  should  be1*  open 
and  porous,  so  tjgit  water  will  be  promptly  absorbed  and 
the  surface  of  trie  ground  will  dry  off  quickly.  As  pre- 
viously indicated,  the  soil  should  be  free  from  insect  pests 
and  disease  parasites ;  to  avoid  trouble  from  such  sources, 
it  may  be  necessary  to  resort  to  steam  sterilization. 


Fig.  50. — Chamber  used  for  the  steam  sterilization  of  soil   in   flats.    (Note  that  the 
flats  are  on  carts.) 

(Fig.  50.)  Some  growers  prefer  to  use  soil  that  is  not 
quite  so  fertile  as  the  soil  used  in  the  beds.  The  tendency 
of  plants  in  very  rich  soil  is  to  make  excessive  leaf  growth 


STARTING  PLANTS  145 

and  poor  root  development,  while  the  opposite  of  this  is 
desirable  in  the  starting  of  all  classes  of  plants.  This 
tendency,  however,  is  not  marked,  if  proper  moisture  and 
temperature  conditions  are  maintained.  See  Chapter  V 
for  details  of  soil  preparation. 

Seed  sowing. — The  time  of  sowing  should  be  deter- 
mined with  extreme  care.  This  will  depend  to  some 
extent  on  the  variety  selected,  for  some  varieties  require 
more  time  to  mature  than  others.  Seasonal  conditions, 
with  special  reference  to  the  amount  of  sunshine  and  the 
rate  of  growth  depending  thereon,  should  also  have  con- 
sideration. But  the  most  important  factor  is  the  demand 
of  the  market  to  be  supplied.  When  will  it  pay  the  best 
prices  for  the  various  crops  and  when  can  they  be  grown 
most  profitably,  are  questions  which  should  be  answered 
if  possible  before  the  seed  is  sown. 

Experience  will  soon  teach  the  greenhouse  gardener 
when  each  sowing  should  be  made,  so  that  he  may  have 
the  seedlings  ready  for  transplanting  at  the  proper  time. 
Experience  will  also  enable  him  to  determine  rather 
definitely  the  quantity  of  seed  to  sow  each  time  in  order 
to  produce  the  required  number  of  plants.  There  should 
be  no  uncertainty,  however,  about  this  matter.  It  is  often 
difficult,  if  not  impossible,  to  make  up  the  shortage  by 
purchasing  plants  that  may  introduce  insect  or  disease 
parasites.  The  safe  policy  is  to  sow  an  ample  quantity 
of  seed,  even  if  thousands  of  plants  must  be  discarded. 
With  a  larger  number  of  plants  than  is  actually  needed, 
only  the  strongest  may  be  used,  and  this  will  count  for 
uniformity  in  size  of  plants  during  the  entire  period  of 
growth. 

The  soil  should  be  fairly  moist  before  the  seeds  are 
sown.  This  is  important  for  two  reasons :  First,  the  soil 
works  better;  second,  it  receives  water  more  rapidly,  and 
the  seeds  are  not  so  likely  to  be  washed  out  of  the  ground 
by  watering. 


146  VEGETABLE   FORCING 

Whether  the  seed  is  sown  broadcast  or  in  drills  is 
largely  a  matter  of  preference.  The  work  may  be  done 
quicker  by  broadcasting.  This  method  also  results  in  a 
more  even  distribution  of  plants,  a  factor  considered  im- 
portant by  some  growers.  On  the  other  hand,  the  drill 
method  makes  possible  the  application  of  water  between 
the  rows  without  wetting  the  plants.  The  plants  arc 
easily  and  quickly  pulled  at  the  time  of  transplanting,  and 
remain  in  better  order  for  this  operation,  thus  saving 
more  time  perhaps  than  the  extra  labor  caused  by  sowing 
in  drills  rather  than  by  broadcasting. 

When  drills  are  used,  the  furrows  for  lettuce,  tomatoes 
and  seeds  of  similar  size  are  usually  about  one-fourth  of 
an  inch  deep.  The  furrows  are  made  with  thin,  narrow 
strips  of  wood,  such  as  a  piece  of  plastering  lath.  The 
seed  may  be  sown  with  the  thumb  and  finger  or  by  the 
use  of  an  envelope. 

Whatever  plan  is  used,  it  is  exceedingly  important  to 
sow  the  seed  thin  enough  to  prevent  crowding.  Ordi- 
narily, eight  to  ten  plants  to  each  linear  inch  of  the  fur- 
row are  as  many  as  will  produce  a  stocky  growth.  If 
the  plants  are  to  be  pricked  out  very  soon  after  they  are 
up,  there  is  no  objection  to  growing  probably  15 
to  the  inch.  The  furrows  are  quickly  closed  by  the  use 
of  the  fingers  or  by  drawing  a  pot  label  along  each  side 
of  the  rows.  After  the  furrows  are  closed  the  soil  should 
be  firmed  with  a  block  of  wood,  and  the  beds  thoroughly 
watered.  Lettuce  is  generally  sown  broadcast. 

Transplanting. — Most  growers  prefer  to  make  the  first 
shift  when  the  rough  or  true  leaves  are  partly  formed, 
which  will  be  in  three  or  four  weeks  from  the  date  of 
sowing.  Others  prick  the  plants  out  in  10  to  15  days,  and 
believe  that  this  practice  is  favorable  to  the  growth  of 
stocky  plants.  It  is  certain  that  there  should  be  no 
crowding  of  the  plants  in  the  flats  or  seed  bed,  and  this 
may  be  prevented  by  thinning  or  early  transplanting. 


STARTING   PLANTS  147 

From  the  standpoint  of  economy  of  space,  early  trans- 
planting is  a  disadvantage,  but  it  is  unquestionably  best 
from  the  standpoint  of  growing  strong,  stocky  plants. 
Lettuce  is  often  transplanted  before  the  true  leaves  are 
formed. 

There  is  the  greatest  diversity  of  practice  in  methods 
of  transplanting.  Spotting  boards  of  different  kinds  are 
made  to  mark  the  soil  in  the  flats  or  beds.  They  may  be 


Fig.  51. — Spotting  board  used  in  transplanting  lettuce. 

provided  with  slight  projections  which  merely  indicate 
the  places  where  the  plants  are  to  be  set  or  they  may 
contain  pegs  (Fig.  51)  which  when  forced  into  the  soil 
and  withdrawn  make  holes  for  the  roots  of  the  plants. 
The  latter  plan  saves  time  and,  properly  executed,  results 
in  straight  rows  uniformly  spaced. 

The  soil  may  be  pressed  firmly  to  the  roots  of  the 
plants  with  the  fingers,  or  a  small  dibber  may  be  found 
convenient  for  this  purpose.  The  plan  should  be  used 
which  is  most  convenient  to  the  gardener.  Soil  of  the 
proper  moisture  content  is  even  more  important  for  trans- 
planting than  for  seed  sowing.  Some  water  is  generally 
applied  after  the  plants  are  shifted,  though  this  is  un- 
necessary if  the  soil  is  as  moist  as  it  can  be  made  without 
being  too  wet.  When  plants  are  shifted  from  pots  of  one 
size  to  those  of  a  larger  size,  a  little  earth  is  first  placed 
in  the  bottom  of  the  pot,  and  soil  is  then  packed  between 
the  ball  of  earth  and  the  side  of  the  pot.  A  common 


148  VEGETABLE  FORCING 

practice  with  many  vegetables  is  to  make  the  first  shift 
into  flats,  and  the  second  and  perhaps  additional  shifts 
into  pots.  A  2-inch  pot  may  be  used  the  first  time,  a  3  or 
4-inch  the  second,  and  if  desired  for  tomatoes  a  5  or  6-inch 
the  third.  More  explicit  directions  for  transplanting  each 
crop  will  be  given  in  later  chapters. 

Care  of  plants. — One  of  the  greatest  dangers  in  the 
starting  of  plants  is  over-watering.  No  more  water 
should  be  used  than  is  necessary  to  keep  the  boxes  or 
beds  moist.  Too  frequent  as  well  as  too  profuse  water- 
ing should  be  avoided.  A  fine  lot  of  plants  may  be  ruined 
by  a  single  careless  watering.  High  temperatures  are 
also  disastrous,  especially  if  there  is  an  excessive  supply 
of  soil  moisture.  Proper  ventilation  is  of  the  greatest 
importance.  See  Chapter  X  on  Watering,  Heating,  Ven- 
tilating and  Shading. 

Damping-off  is  caused  by  fungous  diseases  which  some- 
times play  havoc  among  young  vegetable  plants.  It 
usually  attacks  the  stems  of  the  plants  at  or  near  the 
surface  of  the  ground.  If  the  infection  is  severe,  it  may 
spread  rapidly  over  the  beds  and  cause  many  plants  to 
rot  off  and  die.  The  trouble  may  be  avoided  by  the  use 
of  clean  soil,  by  steam  sterilization,  and  by  proper  ven- 
tilation and  watering.  When  the  disease  is  known  to  be 
present,  watering  only  between  the  rows  will  be  found  to 
be  a  valuable  preventive  measure.  In  other  words,  if  the 
plants  are  kept  dry  there  will  be  less  danger  of  the  fungus 
entering  the  tissues. 


CHAPTER  X 

WATERING,  HEATING,  VENTILATING  AND 
SHADING 

Success  in  the  management  of  greenhouse  crops  de- 
pends more  upon  the  maintenance  of  proper  moisture  and 
temperature  conditions  in  both  soil  and  air  than  upon  any 
other  factors.  Watering,  heating,  ventilating  and  some- 
times shading  are  most  vital  operations  in  the  growing  of 
plants  under  glass. 

Importance  of  water. — Most  of  our  greenhouse  vege- 
tables contain  over  90  per  cent  of  water.  The  amount  of 
water,  however,  which  enters  into  the  composition  of 
plants  is  insignificant  compared  with  that  which  trans- 
pires from  the  surfaces  of  the  leaves.  The  nutrient  solu- 
tion in  a  properly  prepared  soil  is  very  dilute,  and  an 
enormous  quantity  is  absorbed  by  the  plant  in  order  to 
meet  its  food  requirements.  Water  is  the  vehicle  by 
means  of  which  the  nutrients  are  conveyed  to  different 
parts  of  the  plant,  and  while  some  of  it  enters  into  the 
composition  of  the  tissues,  most  of  it  transpires  from  the 
leaves.  It  is  likely  that  the  amount  of  water  which  daily 
transpires  from  the  leaves  of  a  vegetable  plant  in  a  green- 
house, during  the  bright  sunny  weather  in  May  or  June, 
more  than  equals  the  weight  of  the  plant. 

Water  also  performs  various  other  functions,  as  render- 
ing plant  foods  soluble,  giving  rigidity  to  plant  structures 
and  reducing  the  temperature  of  plants.  Aside  from 
these  functions  relating  to  plant  growth,  the  humidity  of 
the  greenhouse,  which  may  be  regulated  by  the  grower, 
will  depend  largely  on  the  use  of  water.  Extremely  low 
humidity  may  be  just  as  harmful  under  certain  condi- 
tions as  extremely  high  humidity. 

149 


150  VEGETABLE  FORCING 

Amount  of  water  required. — An  enormous  amount  of 
water  is  required  to  grow  good  greenhouse  crops.  As 
previously  stated,  it  enters  into  the  composition  of  the 
plants,  but  most  of  the  water  which  enters  the  roots 
escapes  by  transpiration  from  the  leaves.  There  is  also 
rapid  evaporation  from  the  soil.  Wright,  after  making 
a  survey  of  this  question  in  nearly  75  commercial  green- 
house establishments,  estimates  that  the  average  daily 
requirement  of  water  during  the  months  of  May  and  June 
is  280  gallons  per  1,000  square  feet  of  bed  surface  in  crops, 
or  over  12,000  gallons  to  the  acre.  Expressed  in  differ- 
ent terms,  243  gallons  of  water  would  be  required  daily 
per  acre  during  the  months  of  May  and  June,  and  under 
certain  conditions  more  than  that  amount  might  be 
needed,  to  meet  the  requirements  of  the  crops. 

Much  more  water  is  required  during  the  late  spring 
and  early  summer  months  than  through  the  winter.  The 
heat  rays  of  the  sun  are  then  intense,  and  with  the  ven- 
tilators and  doors  open  there  is  the  most  rapid  escape  of 
water  from  both  the  plants  and  the  soil.  Again,  at  this 
season  of  the  year  the  days  are  longer  and  there  is  much 
more  sunshine  than  during  the  winter  months. 

The  character  of  the  weather  at  any  particular  season 
of  the  year  is  also  an  important  factor.  It  is  readily 
understood  that  less  water  will  be  required  on  cloudy 
days  than  in  bright,  sunny  weather,  and  this  matter 
should  have  the  most  careful  consideration  of  the  grower. 

The  kind  of  crop  under  cultivation  is  also  an  important 
factor  to  be  considered.  Generally  speaking,  tomatoes 
and  cucumbers  require  more  water  than  does  lettuce. 

Crops  which  are  well  advanced  or  approaching  ma- 
turity, necessarily  require  more  water  than  young  plants, 
though  there  may  be  diminished  evaporation  from  the 
surface  of  the  beds  because  they  are  shaded  by  the  crops. 

Soils  which  are  very  open  and  porous,  due  to  a  large 


WATERING,    HEATING,    VENTILATING   AND    SHADING      151 

percentage  of  coarse  sand,  require  more  water  because  of 
loss  by  percolation  and  evaporation. 

The  location  of  the  beds  and  heating  pipes  should  be 
considered  with  reference  to  the  water  requirement  of 
the  plants.  If  solid  beds  are  used  and  the  heating  pipes 
are  remote,  less  water  will  be  needed  than  when  raised 
benches  are  employed  with  the  heating  pipes  under  them. 

No  rules  can  be  given  regarding  the  amount  of  water 
which  should  be  applied.  Enough  water  should  be  used 
to  keep  the  soil  moist,  but  over-watering  should  be  care- 
fully avoided,  for  this  makes  soft,  tender  tissues,  and  with 
crops  like  tomatoes  and  cucumbers  may  cause  excessive 
stem  and  leaf  growth  with  a  poor  setting  of  undersized 
fruit.  It  is  possible  to  apply  so  much  water  that  the 
plants  become  stunted  and  refuse  to  make  satisfactory 
growth.  The  dangers  of  over-watering  in  relation  to 
diseases  have  been  indicated  in  previous  chapters. 

Insufficient  watering  may  be  just  as  harmful  as  over- 
watering.  It  necessarily  results  in  small  plants  and  poor  crops. 

It  is  important  to  be  thorough  in  watering.  The  water 
should  be  uniformly  applied  over  the  entire  bed  surface. 
Sometimes  dry  areas  appear  here  and  there,  and  it  is 
often  an  advantage  to  water  these  before  time  for  the 
next  general  watering.  Enough  water  should  be  applied 
each  time  to  moisten  the  soil  to  the  entire  depth  of  the 
beds.  A  few  careful  examinations  of  the  beds,  made 
several  hours  after  each  application  of  water,  will  enable 
the  grower  to  determine  whether  a  sufficient  amount  has 
been  used  to  moisten  the  beds  to  their  full  depths. 

When  to  water. — The  frequency  of  watering  will  de- 
pend on  several  factors.  As  previously  stated,  transpira- 
tion of  water  from  the  leaves  and  evaporation  from  the 
soil  are  much  more  rapid  when  there  is  warm,  sunny 
weather,  and  at  such  times  it  is  necessary  to  apply  water 
more  frequently  than  during  cool,  dull,  cloudy  weather. 
In  the  winter,  when  the  days  are  short  and  there  is  little 


152  VEGETABLE  FORCING 

sunshine,  it  may  be  unnecessary  to  water  oftener  than  once 
a  week,  or  even  at  longer  intervals  under  certain  condi- 
tions. On  the  other  hand,  in  the  summer  it  is  usually 
necessary  to  water  every  day  and  sometimes  twice  daily. 
Whether  it  is  summer  or  winter,  much  less  water  is  re- 
quired on  cloudy  days. 

It  is  always  better  to  water  when  the  temperature  of 
the  greenhouse  is  rising  rather  than  falling.  Unless  the 
water  is  applied  in  a  fine  spray,  it  will  make  the  soil 
cooler,  which,  of  course,  is  undesirable,  but  there  need  be 
no  anxiety  about  this  matter  if  the  temperature  of  the 
houses,  due  to  the  rays  of  the  sun  or  the  heat  from  the 
boiler,  is  gradually  rising.  Then,  too,  in  order  to  prevent 
injuries  from  various  fungous  diseases,  the  foliage  of  the 
plants  should  be  dry  or  free  from  excessive  moisture 
during  the  night.  For  the  two  reasons  just  given  it  is 
preferable  to  water  the  beds  in  the  forenoon,  and  that  is 
the  general  practice  among  greenhouse  growers  of  vege- 
tables and  flowers. 

The  pollination  factor  should  also  have  consideration. 
Pollination  is  most  active  when  neither  the  atmosphere 
of  the  house  nor  the  plants  themselves  contain  much 
moisture.  This  matter  should  be  watched  closely  in 
tomato  and  cucumber  houses,  especially  when  there  is 
dull,  cloudy  weather.  Under  such  conditions  an  abun- 
dance of  water  should  be  used  each  time  so  that  it  will  be 
unnecessary  to  water  more  frequently  than  is  absolutely 
required.  If  the  fruits  are  not  setting  well,  it  will  be  an 
advantage  sometimes  to  use  less  water  than  is  actually 
needed  for  the  plants,  in  order  to  maintain  lower 
humidity,  which  is  favorable  to  the  pollination  of  the 
flowers. 

If  additional  humidity  is  needed  for  any  purpose,  and 
the  beds  should  not  be  watered,  the  walks  may  be  wet 
down  several  times  a  day,  if  necessary. 

It  will  be  seen  from  the  foregoing  remarks  that  no 


WATERING,    HEATING,   VENTILATING   AND   SHADING     153 

rules  can  be  made  relating  either  to  the  amount  of  water 
which  should  be  used  or  the  frequency  of  its  application. 
This  operation  calls  for  the  exercise  of  good  judgment. 
The  plants  themselves  tell  the  experienced  grower  when 
they  are  in  need  of  water.  If  they  wilt  or  even  appear  to 
droop,  there  is  no  question  about  their  requirement,  un- 
less the  heat  of  the  house  is  excessive  and  the  humidity 
unusually  low.  The  color  of  the  leaves  is  a  valuable 
guide  to  the  right  amount  of  water.  Light  green  foliage, 
if  temperatures  are  normal,  indicates  the  use  of  too  much 
water,  while  a  dark  green  color  shows  that  this  factor  is 
being  properly  regulated.  Examination  of  the  soil  is  also 
valuable  in  determining  when  wrater  should  be  applied. 

Temperature  of  water. — Much  has  been  said  in  favor  of 
warming  the  water  during  the  winter,  before  it  is  applied 
to  the  beds.  It  is  doubtful,  however,  whether  instances 
can  be  cited  in  which  the  use  of  cold  water  has  actually 
caused  serious  injury  of  any  kind.  Difficulties  may  arise 
after  the  use  of  cold  water,  but  the  probabilities  are  that 
they  are  due  to  cloudy  weather  or  other  causes  rather 
than  to  cold  water.  The  fact  is,  if  water  is  applied  in  a 
fine  spray,  every  globule  will  take  on  the  temperature  of 
the  air  before  it  reaches  the  soil  or  foliage  of  the  plants. 
In  sub-irrigation,  where  a  stream  of  water  is  turned  into 
the  tile,  there  may  be  some  objection  to  using  cold  water, 
but  even  in  this  case  the  water  would  soon  acquire  the 
temperature  of  the  soil.  However,  there  is  some  evidence 
that  the  use  of  warm  water  in  sub-irrigation  tile  is  an 
advantage  to  crops  requiring  especially  warm  soils. 

Methods  of  watering. — Various  factors  should  be  taken 
into  account  in  the  consideration  of  different  methods  of 
watering.  Among  them  may  be  mentioned : 

(1)  Cost  of  installation.    The  cost  of  installing  a  given 
system  may  be  slight,  but  if  it  is  unsatisfactory  there  is 
no  justification  for  its  use. 

(2)  Effect  on  plant  growth.    One  system  may  be  better 


154 


VEGETABLE   FORCING 


than    another,    as    shown    by    larger    and    better    crops. 

(3)  Uniform  distribution  of  water.     A  system  which 
does  not  distribute  the  water  evenly  over  the  entire  area 
of  the  beds  cannot  give  the  best  results. 

(4)  Effect  on  soil.    Some  systems  of  watering  compact 
the  soil,  and  cause  the  formation  of  hard  incrustations 
on  the  surface  of  the  beds.     This  effect  is  objectionable 
because  it  prevents  the  proper  aeration  of  the  soil  and 
necessitates  frequent  tillage  to  break  up  the  crust. 

(5)  Mechanical  injury  to  the  plant.     This  may  occur 
if  a  stream  of  water  is  forced  against  the  plants  through 
a  nozzle  which  is  not  properly  adjusted. 

(6)  Labor  cost.     This  factor  should  have  special  con- 
sideration.    It  is  inefficiency  to  devote  hours  or  days  to 
work  which  might  be  accomplished  by  means  of  me- 
chanical devices  that  require  very  little  attention. 

Watering  can  and  hose. — In  the  early  days  of  green- 
house cropping,  all  of  the  water  was  applied  with  water- 

, ,     ing  cans.    It  is  a 

slow,  laborious 
method  that 
should  not  be 
used  in  any  com- 
mercial estab- 
lishment, except 
in  starting  small 
lots  of  plants.  A 
step  in  advance 
was  made  when 
the  hose  was  at- 
tached to  the 
spigot,  and  water 
applied  direct  to  the  beds.  Some  growers  use  the  hose 
without  any  nozzle,  and  this  may  be  desirable  if  profuse 
watering  is  necessary,  as  during  the  summer  months 
when  cucumber  plants  have  attained  full  development 


Fig.  52. — A  convenient  form  of  nozzle 
for   greenhouse    watering. 


WATERING,    HEATING,   VENTILATING   AND   SHADING     155 

and  the  crop  is  being  harvested.  Ordinarily,  it  is  prefer- 
able to  apply  water  in  a  fine  spray  or  mist,  and  this  is  not 
possible  without  the  use  of  a  special  nozzle  which  may  be 
attached  to  the  hose.  Fig.  52  shows  a  most  serviceable 
nozzle  for  the  watering  of  small  plants,  and  it  is  also  con- 
venient for  watering  limited  areas  here  and  there  which 
may  need  water  before  the  time  of  the  next  general  water- 
ing. Some  form  of  hose  watering  is  used  more  or  less  in 
all  commercial  establishments.  A  combination  of  two 
systems  is  ideal.  For  example,  sub-irrigation  is  highly 
satisfactory  for  lettuce,  but  many  growers  prefer  the  hose 
or  perhaps  the  overhead  system  for  cucumbers,  partly  be- 
cause they  are  valuable  in  controlling  the  red  spider. 
The  hose  and  overhead  watering  also  make  a  desirable 
combination.  Though  the  expense  of  installing  two  sys- 
tems of  watering  may  seem  excessive,  the  advantages 
thereof  may  more  than  justify  the  additional  expenditure. 

Watering  with  a  hose,  unless  carefully  managed,  may 
result  in  the  incrustation  of  the  surface  of  the  soil.  To 
avoid  this  difficulty,  the  spray  should  be  as  fine  as 
possible  and  the  hose  should  not  be  held  too  long  at  one 
place. 

Sub-irrigation. — Several  agricultural  experiment  sta- 
tions have  conducted  experiments  in  the  watering  of 
greenhouse  vegetable  crops  by  means  of  sub-irrigation. 
The  work  of  the  Ohio  station  has  attracted  most  atten- 
tion. In  the  institutions  where  sub-watering  has  been 
tried,  the  results  have  generally  been  favorable  to  this 
system.  For  reasons,  however,  which  cannot  be  satis- 
factorily explained,  sub-irrigation  has  not  become  popular 
among  commercial  greenhouse  men.  A  grower  here  and 
there  is  using  the  system,  but  the  rank  and  file  of  the 
gardeners  who  produce  crops  under  glass  have  not 
adopted  this  plan  of  watering.  It  is  presumably  due  to 
the  cost  of  installation.  There  is  also  some  objection  to 
having  the  tile  in  the  beds  where  they  interfere  more  or 


156  VEGETABLE  FORCING 

less  with  the  soil  preparation.  An  experienced  grower 
states  that  three  to  five  times  as  much  water  is  required 
for  sub-irrigation  in  beds  that  are  not  water-tight  as  with 
surface  watering,  and  this  is  a  serious  objection  when  the 
supply  of  water  is  limited  or  expensive. 

There  seems  to  be  no  difference  of  opinion  concerning 
the  advantages  of  sub-irrigation,  which  may  be  enumer- 
ated as  follows : 

(1)  The  surface  of  the  beds  remains  dry.    This  lessens 
the  dangers  of  fungous  diseases,  especially  of  lettuce,  and 
obviates  the  necessity  of  frequent  tillage. 

(2)  The  surface  of  the  bed  remains  open  and  porous, 
thus  providing  perfect  soil  aeration  without  the  use  of 
tillage  implements.    From  this  standpoint,  sub-irrigation 
possesses  special  advantages  for  heavy  soils. 

(3)  Less  labor  is  required  to  water  the  houses  than 
when  a  hose  is  used. 

(4)  With  sub-irrigation  it  is  possible  to  maintain  lower 
humidity  than  with  any  form  of  surface  watering.    This 
is  a  special  advantage  in  controlling  certain  diseases  and 
in  providing  the  most  favorable  atmospheric  conditions 
for  pollination. 

(5)  The  tile  may  be  used  for  steam  sterilization  as  well 
as  for  watering,  and  thus  the  expense  avoided  of  special 
sterilizing  equipment,   and   the   labor   of  shifting  pans, 
pipes  and  perhaps  moving  the  soil  whenever  the  beds  are 
sterilized. 

(6)  The  tile  may  also  be  used  for  heating  the  beds  by 
admitting  steam  at  low  pressure.    Some  good  results  have 
been  reported  relating  to  this  practice. 

(7)  Sub-irrigation  is  the  means  of  avoiding  any  me- 
chanical injury  to  the  plants,  which  sometimes  occurs 
when  nearly  mature  lettuce  is  weighted  down  by  water 
applied  above  the  beds. 

(8)  It  is  unnecessary  to  water  so  frequently  when  sub- 
irrigation  is  used. 


WATERING,    HEATING,    VENTILATING   AND    SHADING      157 

(9)  According  to  growers  who  have  had  considerable 
experience  with  this  system,  over-watering  is  impossible 
when  water  is  applied  through  tiles  laid  in  beds  that  are 
not  water-tight.    This  unquestionably  is  one  of  the  great- 
est advantages  of  sub-irrigation. 

(10)  Larger  yields  are  often  obtained  with  sub-irriga- 
tion. 

This  method  of  watering,  as  seen  in  Fig.  53,  may  be 
used  on  raised  benches  as  well  as  in  beds  on  the  ground. 
It  is  necessary,  of  course,  for  the  benches  to  be  water- 


Fig.  53. — Tile  laid  in   bed   for   sub- irrigation. 

tight,  which  involves  an  additional  expense  that  must  be 
charged  to  the  cost  of  installing  the  system.  Inasmuch 
as  benches  are  not  generally  used  in  extensive  vegetable- 
forcing  establishments,  it  is  seldom  that  we  find  benches 
constructed  for  sub-irrigation.  Aside  from  the  expense, 
it  is  a  simple  matter  to  make  reinforced  benches  with 
concrete  bottoms  and  sides  which  will  be  entirely  water- 
tight. Such  beds  should  be  not  less  than  6  inches  deep. 

B.  H.  Thome,  who  had  12  years  of  experience  in  the 
use  of  this  system,  claimed  that  it  is  not  desirable  to  have 
the  ground  beds  water-tight,  because  there  is  then  no 
danger  of  over-watering.  There  are  two  main  points  to 


158  VEGETABLE  FORCING 

be  considered :  First,  the  tile  lines  must  be  laid  level,  and, 
second,  there  must  be  water-tight  walls  around  the  beds, 
which  may  be  of  any  convenient  size.  Beds  need  not  be 
more  than  6  inches  deep,  though  8  to  10  inches  will  give 
better  results,  and  some  growers  prefer  them  even  deeper 
than  10  inches. 

Pipes  of  various  sizes  may  be  used,  but  tile  are  more 
satisfactory  as  well  as  more  economical.  Tile  2^  inches 
in  diameter  are  preferred  if  they  must  be  laid  near  the 
surface  of  the  beds,  and  3-inch  size  is  best  if  they  are  to 
be  placed  4  or  5  inches  or  more  below  the  surface  of  the 
ground.  In  shallow  beds  the  tile  need  not  be  covered  with 
more  than  an  inch  or  two  of  soil.  If  the  soil  is  light,  open 
and  porous,  it  is  better  to  place  the  tile  near  the  surface 
of  the  beds  rather  than  at  a  depth  of  10  inches  or  more, 
because  less  water  will  be  required.  In  shallow  beds  of 
light  soil,  the  first  line  of  tile  should  be  10  inches  from 
the  wall  of  the  bed,  and  the  interior  lines  should  be  about 
2^  feet  apart,  though  3  feet  is  permissible.  In  the 
deeper  beds  it  is  customary  to  place  tile  18  inches  to  2 
feet  apart.  The  concrete  walls,  if  well  made,  need  not  be 
more  than  2^  inches  thick. 

A  little  mud  mortar  placed  at  each  joint  will  hold  the 
tile  in  place  while  they  are  being  laid  and  until  the  beds 
have  been  filled  with  soil.  Deep  beds  require  more  water 
than  shallow  ones,  but  applications  need  not  be  so  fre- 
quent. There  does  not  seem  to  be  any  uniform  practice 
in  regard  to  the  length  of  the  lines  of  tile.  If  they  are 
carefully  placed,  with  the  joints  as  close  together  as 
possible,  and  there  is  an  abundant  flow  of  water,  the  lines 
may  be  50  feet  long.  At  the  ends  of  such  lines,  elbows 
are  used  to  provide  outlets  above  the  surface  of  the 
ground,  and  pipe  headers  may  be  used  to  connect  with 
several  lines  of  tile.  It  is  then  possible  to  water  a  9  x  50 
bed  in  five  hours  or  less,  the  time  depending  upon  the 


160  VEGETABLE  FORCING 

volume  of  water  available  as  well  as  upon  the  rate  of  flow, 
depth  of  bed  and  character  of  soil. 

During  the  winter  months,  one  watering  may  last  for 
five  weeks  or  longer,  and  in  the  summer  it  may  not  be 
necessary  to  water  oftener  than  once  a  week  or  every  10 
days.  In  newly  planted  beds,  especially  if  the  plants  are 
small,  it  is  necessary  to  make  one  or  two  surface  water- 
ings until  the  plants  have  become  established. 

Thorne  recommends  that  the  tile  be  cleaned  and  relaid 
every  third  year. 

Sub-irrigation  is  considered  especially  desirable  for 
lettuce  and  tomatoes. 

Overhead  irrigation. — Of  the  various  systems  of  water- 
ing greenhouse  vegetable  crops,  overhead  irrigation 
(Fig.  54)  is  the  most  generally  used  in  large  commercial 
establishments.  Wright,  in  a  recent  survey  of  extensive 
ranges  used  for  the  forcing  of  vegetables,  found  that  78 
growers  out  of  100  were  employing  the  overhead  system. 
The  advantages  of  this  system  are  as  follows : 

(1)  Comparatively  small  cost  of  installation.    It  is  esti- 
mated by  the  manufacturers  that  the  cost  will  usually  be 
about  $300  an  acre.    This  is  very  much  less  than  the  ex- 
pense involved  in  preparing  the  beds  for  sub-irrigation. 

(2)  The   water   is   applied    more    uniformly   than   is 
possible   with   any   other  system   except   sub-irrigation. 
There  should  be  no  wet  spots  anywhere  in  the  house 
when  the  overhead  system  of  watering  is  employed. 

(3)  The  labor  of  watering  is  very  slight.    Only  a  few 
moments  are  required  to  open  the  valves  and  to  turn  the 
nozzle  lines  as  may  be  necessary  to  water  the  entire 
house.    An  automatic  turning  device  has  been  invented 
recently    which    should    further    reduce    the    attention 
required  by  this  system  in  the  watering  of  greenhouse 
crops. 

(4)  The  patented  nozzles  diffuse  the  water  into  an  ex- 
tremely fine  mist,  which  then  descends  gently  upon  the 


WATERING,    HEATING,    VENTILATING   AND    SHADING      161 

plants  and  beds.  In  effect  it  is  like  a  very  fine  rain.  If 
the  beds  have  been  properly  prepared,  the  water  will  not 
stand  on  them  and  there  will  be  practically  no  incrusta- 
tion on  the  surface  of  the  beds,  nor  will  the  fine  mist 
compact  the  soil.  Again,  there  need  be  no  fear  of  the  fine 
mist  causing  mechanical  injuries  to  the  plants. 

(5)  With  the  overhead  system  the  hot,  dry  atmosphere 
of  the  greenhouse  may  be  changed  in  a  few  minutes. 
This  is  often  a  great  advantage  in  the  summer  for  a  crop 
like  cucumbers. 

(6)  It  is  also  possible  to  apply  fungicides,  insecticides 
and  liquid  fertilizers  through  the  overhead  system  of 
pipes  and  nozzles. 

The  main  flow  or  feeder  line  should  run  across  the 
house,  and  it  is  usually  most  convenient  to  have  it  at  the 
end  near  the  boiler  room  or  packing  room.  It  should  be 
amply  large,  to  meet  the  demands  of  the  houses.  The 
following  table,  furnished  by  the  manufacturers  of  a 
popular  system,  may  be  followed  in  determining  the 
proper  size  of  the  main  supply  line : 

LENGTH  OF  LINE 

50ft    100ft    200ft    300ft    400ft    500ft    600ft    700ft 

30  gal.  per  min.  l]/2        2  2  2  2J4         2'/£         2J4         2*/2 

75  gal.  per  min.  2  2^         2^         2^         3  3  3  3 

100  gal.  per  min.  2^        2^        3  3  3  3^         3^         3^ 

150  gal.  per  min.  2^        3  3  3^         S*/2         3^         4  4 

200  gal.  per  min.  3  3J4         3^         4  4  4  44 

300  gal.  per  min.  3*<£        3*4        4  4  4  4  5  5 

400  gal.  per  min.  44455556 

500  gal.  per  min.  45556666 

Nozzles  or  distributing  lines  connect  at  right  angles 
with  the  supply  line.  The  connection  is  made  with  a 
patented  swivel  union,  which  makes  it  possible  to  turn 
the  line  with  a  lever,  in  order  that  all  of  the  ground  may 
be  evenly  watered.  The  nozzle  lines  are  placed  16  feet 
apart,  so  that  two  lines  would  meet  the  requirements  of  a 
house  32  feet  wide,  three  lines  for  a  house  48  feet  wide, 
etc.  The  nozzle  lines  may  be  500  feet  long  if  necessary. 
The  size  of  the  pipe  will  depend  on  the  length  of  the  line, 


162  VEGETABLE  FORCING 

the  pressure  of  the  water  and  the  nozzle  to  be  used.  It 
is  better  not  to  have  too  great  a  length  of  pipe  of  any 
one  size. 

The  following  table,  prepared  by  the  manufacturers 
of  an  approved  system,  will  be  found  valuable  in  estimat- 
ing the  pipe  requirements : 

SIZES  OF  PIPE  FOR  GREENHOUSE  NOZZLE  LINES 

Calculated  on  greenhouse  nozzles  placed  3  feet  apart  in  the  line.    If 
the  nozzles  are  closer  together  larger  pipe  must  be  used 

Nozzle      Total  length  of    No.  feet    No.  feet      No.  feet        No.  feet        No.  feet 
No.  line  in  feet         fi"  pipe      1"  pipe      lJ4"pipe        l^'pipe        2*  pipe 


125 


100 

100 

— 

— 



Greenhouse 
No.  2 

150 
250 
300 

75 
75 
75 

75 
75 

75 

100 
100 

50 

500 

75 

75 

100 

125 

75 

75 

— 







100 

60 

40 

— 





150 

60 

60 

30 





250 

40 

60 

75 

75 



300 

40 

60 

75 

75 

50 

400 

40 

60 

75 

75 

150 

Greenhouse 
No.  3 


50  50  _ 

Greenhouse    100  40  60      •      

No.  4      150  40  50  60  — 

250  35  40  75  100 


Greenhouse 
No.  5 


30 

30 

— 



__ 

70 

20 

50 





100 

20 

50 

30 

__ 

150 

20 

50 

40 

40 

250 

20 

30 

60 

60 

80 


The  nozzles  on  the  greenhouse  lines  are  generally 
placed  3  feet  apart.  The  theoretical  discharge  from  100 
No.  2  or  No.  3  greenhouse  nozzles,  according  to  estimates 
of  the  manufacturers,  is  shown  in  the  following  table : 


WATERING,    HEATING,   VENTILATING  AND   SHADING     163 


THEORETICAL  DISCHARGE  OF  100  NOZZLES  IN  U.  S.  GALLONS 
PER  MINUTE 

The  No.  1  outdoor  nozzles  and  the  No.  3  greenhouse  nozzles  are 
the  sizes  most  generally  used 

, Head ^  , Type  nozzles v 

Pounds  Feet  Greenhouse  No.  2      Greenhouse  No.  3 

5  11.55  11.5  176 

10  23.1  16.3  25.1 

15  34.7  19.9  30.8 

20  46.2  23.1  35.4 

25  57.8  25.8  38.6 

30  69.3  28.4  43.3 

35  80.9  30.6  46.9 

40  92.4  32.6  50.2 

The  nozzle  lines  in  the  greenhouse  may  be  supported 
by  special  hangers  provided  for  the  purpose.  Holes  in 
the  pipe  for  the  brass  nozzles  are  made  by  a  special  drill- 
ing machine.  It  is  not  a  difficult  matter  to  install  an 
overhead  system  of  watering,  and  the  manufacturers  are 
always  pleased  to  give  instructions  on  any  point  which 
may  not  be  fully  understood.  Whenever  a  pressure  of 
10  pounds  or  more  can  be  obtained,  it  is  possible  to  op- 
erate the  overhead  system  of  watering,  though  a  higher 
pressure  makes  a  finer  spray.  In  fact,  practical  growers 
prefer  a  pressure  of  not  less  than  25  pounds,  and  40 
pounds  is  better. 

Temperature.— The  proper  temperatures  for  the  various 
greenhouse  crops  will  be  discussed  in  later  chapters.  It 
should  be  said  here,  however,  that  a  uniform  tempera- 
ture is  important,  unless  sunshine  should  cause  a  wide 
range  in  temperature,  which  will  do  no  harm  if  free  venti- 
lation is  given.  An  inadequate  heating  plant  may  be 
responsible  for  low  temperatures  that  are  disastrous  to 
the  crops.  Ordinarily,  excessively  high  temperatures 
with  poor  ventilation  do  more  harm  than  insufficient  heat. 

Ventilation.— The  necessity  of  ventilation  was  dis- 
cussed in  Chapter  VIII  on  Diseases  and  Their  Control. 
Every  practical  grower  knows  that  plants  in  houses  im- 


164  VEGETABLE   FORCING 

properly  ventilated  soon  become  tender  and  spindling, 
and  they  are  then  especially  subject  to  the  attack  of 
fungous  diseases.  Abundant  ventilation  is  necessary  in 
order  to  grow  strong,  vigorous  plants.  The  direct  effects 
of  ventilation  are  to  reduce  the  humidity,  to  lower  the 
temperature  and  to  increase  transpiration  of  water  from 
the  leaves  and  evaporation  from  the  soil.  Good  judgment 
must  be  exercised  in  ventilating.  Too  much  ventilation 
under  certain  conditions  may  be  just  as  harmful  as  too 
little.  Admitting  fresh  air  increases  the  circulation .  of 
air  in  the  houses,  and  this  may  be  of  special  value  in  re- 
ducing humidity  and  in  preventing  or  checking  fungous 
diseases.  Too  much  ventilation  is  impossible  during  the 
summer  months.  In  the  winter  time  care  should  be  taken 
to  prevent  cold  drafts  from  coming  into  direct  contact 
with  the  plants. 

The  usual  custom  is  to  open  the  ridge  ventilators  as 
much  as  may  be  possible  in  the  forenoon,  when  the  tem- 
perature in  the  houses  is  rising,  and  to  close  them  some- 
time in  the  afternoon.  If  the  weather  is  fairly  mild,  they 
should  be  opened  early  in  the  morning  and  closed  late 
in  the  afternoon.  In  the  summer  they  are  left  open  day 
and  night,  except  on  the  approach  of  severe  storms,  when 
they  should  be  closed  to  protect  both  crops  and  houses 
from  possible  damage. 

Shading  the  houses  is  sometimes  an  advantage  or  even 
a  necessity.  Whitewash  made  from  air-slaked  lime  is 
generally  used.  Cucumbers  seem  to  be  most  benefited  by 
shading. 


CHAPTER  XI 
MARKETING 

The  growing  of  vegetable  crops  under  glass  is  an  ex- 
pensive proposition.  Land  of  high  value,  usually  near 
a  city,  is  selected  for  the  establishment.  If  a  considerable 
area  is  covered,  large  sums  of  money  must  be  spent  for 
construction,  maintenance,  heating,  labor,  equipment, 
water,  manure,  etc.  Depreciation,  interest  on  the  invest- 
ment, fire  and  hail  insurance  and  probable  losses  must 
also  be  taken  into  consideration.  Production  costs  under 
glass  are  necessarily  much  higher  than  out  of  doors.  This 
fact  should  be  kept  in  mind  by  the  greenhouse  market 
man.  If  a  profit  is  to  be  realized,  much  better  prices  must 
be  obtained  for  the  forced  products  than  for  vegetables 
grown  in  the  open.  In  other  words,  modern  methods  of 
marketing  must  be  employed  if  the  venture  is  to  prove 
a  satisfactory  business  proposition. 

The  most  skillful  marketing,  however,  cannot  do  every- 
thing toward  making  the  business  a  financial  success.  So 
much  is  being  said  about  better  marketing  that  there  is 
danger  of  losing  sight  of  the  equally  important  factor  of 
successful  production,  especially  in  regard  to  quality. 
The  high  cost  of  production  makes  it  imperative  to  grow 
the  best,  and  the  most  approved  methods  of  marketing 
will  fail  to  make  the  business  yield  satisfactory  dividends 
unless  vegetables  of  the  highest  quality  are  available  from 
day  to  day.  High  quality,  economic  production  and  skill- 
ful marketing  are  the  factors  that  win  large  profits. 

Psychology  of  successful  salesmanship. — The  appear- 
ance of  an  article  when  offered  for  sale,  more  than  any 
other  factor  of  marketing,  determines  the  price  that  can 
be  obtained  for  it.  This  statement  applies  to  food  prod- 
ucts just  as  well  as  to  clothing,  household  furnishings  or 

165 


166  VEGETABLE  FORCING 

automobiles.  If  an  article  is  not  attractive  it  is  not  likely 
to  sell  well.  Vision  must  be  appealed  to  if  we  wish  to 
make  prompt  sales  at  good  prices.  When  the  eye  is 
pleased,  the  mind  usually  decides  quickly  and  favorably 
as  to  the  value  of  the  article.  This  is  practical  psychology 
applied  to  salesmanship. 

Now,  various  factors  are  involved  in  the  art  of  making 
greenhouse  vegetables  attractive  when  offered  for  sale. 
The  variety  grown  is  an  important  consideration.  For 
example,  curly-leaf  lettuce  is  much  more  pleasing  in  ap- 
pearance than  plain  sorts,  and  bright  red  tomatoes  are 
preferable  to  dull  red  specimens.  The  form  of  the  product 
is  also  important.  No  one  would  claim  that  an  ill-shaped 
cucumber  is  as  attractive  as  one  that  is  uniformly 
cylindrical  except  at  the  ends. 

Numerous  illustrations  might  be  given  to  show  that  both 
color  and  form  are  important  factors  in  relation  to  the 
attractiveness  of  vegetables.  The  choicest  and  finest  ones 
will  fail  to  fully  please  the  eye  of  the  prospective  pur- 
chaser unless  they  are  graded  and  packed  in  the  proper 
manner.  Packages  which  are  small,  neat,  clean  and  con- 
venient appeal  to  the  vision,  and  if  they  are  filled  with 
superior  vegetables,  tastefully  arranged,  they  will  not  fail 
to  command  attention. 

Mention  should  also  be  made  in  this  connection  of  ty- 
ing materials,  oiled  paper,  labels,  trademarks,  etc.,  which 
not  only  attract  attention,  but  convey  the  impression 
that  the  vegetables  are  of  special  quality.  The  appear- 
ance of  the  market  wagon  and  team,  or  of  the  delivery 
truck,  as  well  as  the  neatness  and  personality  of  the  sales- 
man, should  also  have  consideration. 

Harvesting. — Each  crop  should  be  harvested  at  the 
proper  time  to  obtain  the  highest  yield  without  sacrificing 
quality.  Over-ripeness  should  be  carefully  avoided,  for 
such  a  condition  always  impairs  quality. 

Various  kinds  of  baskets  and  crates  are  used  in  gather- 
ing the  crops.  If  the  houses  are  small  the  products  are 


MARKETING 


167 


usually  carried  to  the  packing  room.  In  large  establish- 
ments, wheelbarrows  or  special  carts  (Figs.  55,  56  and 
57)  are  employed,  and  wide  alleys  and  corridors  may  be 
provided  for  their  use.  It  is  not  a  light  task  to  harvest 
the  crops  under  several  acres  of  glass,  and  growers  will 
do  well  to  consider 
conveniences  which 
will  make  the  work 
less  expensive  as 
well  as  pleasanter. 
Packing  room. — 
The  packing  room 
(Fig.  58)  should  be 
easily  accessible 
from  all  parts  of 
the  range.  It  is  an 
advantage  to  have 
it  close  to  the  boiler 
room  for  the  con- 
venience of  laborers 

who     mififht    be     re-          fis-  55. — A  convenient  homemade  cart  for 
.     .  .  .     7  •          handling  two  barrels  at  a  time. 

quired  in  both  places. 

It  should  be  of  ample  size,  to  avoid  crowding  and  to 
promote  the  work  by  proper  organization  and  system. 
The  floor  should  be  of  concrete,  with  a  gentle  slope  to  one 
or  more  drains.  A  wooden  or  metal  wash  tank  with  a 
drain  board  at  each  end  should  be  placed  in  the  central 
part  of  the  room.  Ordinary  bath  tubs  are  excellent  for 
this  purpose.  An  abundance  of  clean,  running  water  is 
essential.  Tables  or  benches  of  convenient  height  are 
placed  around  the  walls  of  the  room.  There  should  be  a 
sufficient  number  of  windows  to  light  the  room  well  by 
day,  and,  since  it  is  sometimes  necessary  to  work  at  night, 
good  artificial  lights  should  be  provided. 

The  greenhouse  packing  room  should  be  large  enough 
to  accommodate  the  market  wagons  or  delivery  trucks 
necessary  to  handle  the  crop.  It  is  an  advantage  to  have 


168  VEGETABLE  FORCING 

a  driveway  at  one  side  of  the  room  so  that  the  floors  of 
the  wagons  or  trucks  will  be  on  the  same  level  as  the 
floor  of  the  packing  room.  Provision  must  also  be  made, 
usually  above  the  packing  room,  for  a  liberal  supply  of 
crates  or  baskets. 

Packages. — The  greatest  care  should  be  exercised  in 
the  selection  of  packages  for  the  handling  of  greenhouse 
products.  Baskets  or  crates  used  for  products  grown  in 
the  open  may  not  be  satisfactory  for  the  higher  quality 
vegetables  grown  under  glass.  Small  packages  are  gain- 


Fig.  56. — A  handy  cart   for  greenhouse   use. 

ing  in  popularity.  Vegetables  generally  sustain  less  in- 
jury in  transportation  in  small  packages,  and  the  small 
package  is  usually  more  attractive.  There  is  nothing 
especially  attractive  about  a  barrel,  but  a  neat  little  box 
or  basket,  filled  with  choice  vegetables,  naturally  appeals 
to  the  consumer,  and  in  most  instances  to  the  dealer.  The 
small  package  is  of  greater  advantage  also  to  both  pro- 
ducer and  dealer  than  most  of  them  realize. 

Suppose,  for  example,  that  lettuce  is  shipped  in  barrels. 
The  retailer  who  obtains  a  barrel,  and  whose  trade  is 
limited,  may  not  sell  more  than  one-third  of  the  lettuce 


MARKETING  169 

the  first  day.  The  remaining  heads  are  more  or  less 
wilted  by  the  second  day,  and  they  do  not  appeal  to  the 
buyers,  so  that  fewer  sales  are  made  on  that  day.  The 
lettuce  is  in  much  worse  condition  the  third  day,  and  the 
day  closes  with  a  remnant  so  inferior  that  it  cannot  be 
sold  at  all.  The  dealer,  of  course,  is  reluctant  to  buy 
another  barrel  of  lettuce  until  disposition  has  been  made 
of  the  previous  lot.  His  sales  and  profits  are  diminished, 
the  consumer  is  disappointed,  and  the  producer  wonders 
why  his  lettuce  does  not  sell  better.  Had  the  small  grocer 
bought  a  bushel  box  or  perhaps  two  half  bushel  baskets 
of  lettuce,  there  would  have  been  no  dissatisfaction  at 
any  point  from  producer  to  consumer,  because  a  fresh 
lot  of  lettuce  would  be  offered  for  sale  every  day.  There 
are  good  reasons,  sometimes,  for  using  barrels  for  the 
shipment  of  lettuce,  but  the  illustration  applies  to  thou- 
sands of  stores  where  various  kinds  of  greenhouse  prod- 
ucts are  handled  in  packages  that  are  too  bulky  for  the 
best  results. 

The  style  or  form  of  the  package  should  have  con- 
sideration. Small  baskets  with  handles  always  appeal  to 
buyers.  Variously  designed  carriers  are  in  use,  which 
seem  to  meet  the  demands  of  dealers.  This  subject  will 
be  more  fully  discussed  in  connection  with  notes  on  the 
marketing  of  each  crop. 

The  bushel  box  and  other  smaller  wooden  and  paper 
boxes  and  rectangular  crates  of  various  descriptions  are 
popular  because  they  can  be  loaded  solidly  on  wagons, 
trucks  and  cars  without  any  loss  of  space.  It  is  a  great 
advantage  to  use  uniform  and  standard  types  and  sizes 
in  each  community,  and  uniformity  in  this  matter 
throughout  the  country  would  be  of  inestimable  benefit 
to  the  vegetable-forcing  industry. 

Preparation  for  market. — Inasmuch  as  greenhouse  prod- 
ucts are  usually  of  special  quality  and  in  many  instances 
easily  bruised  or  damaged,  it  is  necessary  to  handle  them 
with  extreme  care.  They  are  taken  promptly  to  the  pack- 


170 


VEGETABLE  FORCING 


ing  room,  where  they  are  prepared  for  market.  Cleanliness 
is  essential.  In  many  instances  very  little  attention  will 
be  needed  to  remove  any  soil  or  dirt  that  may  adhere  to 
the  vegetables.  The  use  of  a  moist  cloth  may  be  sufficient 
to  secure  proper  cleanliness,  though  it  is  sometimes  nec- 
essary to  wash  the  vegetables. 


Fig.  57. — Harvesting   a   crop  of  cucumbers  in   a   large  range. 

Special  emphasis  should  be  placed  on  the  importance 
of  careful  grading.  It  is  a  good  business  proposition  to 
practice  rigid  grading.  A  reputation  for  uniformity  in 
the  vegetables  offered  for  sale  cannot  be  established  with- 
out rigid  grading.  With  most  greenhouse  products  it  is 
desirable  to  make  three  grades.  Size,  color,  shape,  mark- 
ings, degree  of  ripeness  and  defects  of  various  kinds 
should  be  taken  into  account. 

Packing. — Not  only  must  the  vegetables  be  clean  and 
properly  graded,  but  they  should  be  arranged  or  packed 
in  the  most  attractive  manner.  A  pleasing  appearance 
secured  in  packing  may  be  obtained  by  the  careful  place- 


MARKETING 


171 


ment  of  every  specimen,  so  that  the  arrangement  of  layers 
and  rows  of  individual  specimens  will  be  orderly  and 
systematic.  Lining  the  inside  of  packages  with  white  or 
perhaps  colored  paper  produces  a  pleasing  effect.  At- 
tractiveness is  often  secured  by  wrapping  each  specimen 
with  soft  paper,  which  may  bear  the  name  and  address 
of  the  grower.  The  use  of  paper  in  this  way  also  helps 
to  insure  the  safe  transportation  of  the  vegetables  with- 
out bruises  or  other  mechanical  injuries.  Radishes,  rhu- 
barb, etc.,  tied  with  blue  or  red  tape  always  present  a 
pleasing  appearance. 

Honest  packing  is  absolutely  essential.  The  vegetables 
at  the  bottom  of  the  package  should  be  just  as  good  as 
those  on  the  top.  If  there  is  any  difference  in  this  re- 
spect, it  is  better  to  have  the  specimens  of  less  merit  on 
the  top.  This  will  not  only  be  an  agreeable  surprise  to 
the  dealer  or  to  the  consumer  as  the  package  is  emptied, 
but  it  may  cause  him  to  place  another  order  with  the 
grower  who  has  not  deceived  him.  However,  it  is  always 
better  to  have  the  produce  run  uniform  throughout  the 
package. 

It  is  also  important  to  give  full  measure.  Partly  filled 
packages,  though  the  vegetables  may  be  of  the  highest 


Fig.  58. — Corner   of   packing   room    in    a  well-managed    establishment. 


172  VEGETABLE   FORCING 

quality,  do  not  appeal  to  buyers.  They  invariably  give 
the  impression  that  the  grower  is  endeavoring  to  get  full 
prices  for  packages  of  vegetables  which  do  not  represent 
full  value.  It  is  a  mistake  to  follow  such  a  practice.  In 
the  long  run  the  grower  will  gain  by  showing  liberality 
and  generosity  in  giving  full  or  even  heaped-up  measure 
wherever  covers  are  not  required  for  shipment. 

Methods  of  selling. — Hundreds  of  vegetable-forcing 
establishments  are  located  near  good  markets  that  may  be 
reached  by  wagon  or  auto  delivery  trucks.  Whenever 
this  is  possible,  the  problem  of  marketing  is  compara- 
tively simple.  Other  large  establishments  are  located  so 
far  from  market  that  practically  the  entire  crop  must  be 
transported  by  rail. 

A  great  many  different  methods  are  employed  in  selling 
greenhouse  crops.  Where  the  business  is  conducted  on  a 
large  scale,  it  is  customary  to  sell  through  commission 
and  wholesale  houses.  In  other  cases  wagons  and  trucks 
deliver  the  products  to  retail  stores  and  hucksters,  and 
this  is  the  most  common  plan  whenever  two  acres  or  less 
of  glass  is  employed.  Parcel  post  shipments  are  made  to 
a  very  limited  extent.  It  is  apparent  that  our  growers,  as 
a  rule,  do  not  care  to  look  up  a  trade  which  might  be 
supplied  by  parcel  post,  nor  do  they  want  to  attend  to  the 
multitude  of  details  demanded  by  this  system  of  market- 
ing. Theoretically,  it  seems  practicable,  but  it  has  not 
appealed  to  greenhouse  growers.  The  extra  labor  re- 
quired may  be  the  greatest  barrier  to  the  adoption  of  the 
system. 

Delivery  trucks  and  wagons. — Auto  delivery  trucks  are 
in  common  use  among  greenhouse  growers.  They  have 
largely  superseded  wagons.  The  chief  advantages  of  an 
auto  delivery  truck  may  be  enumerated  as  follows  : 

(1)  It  enables  a  gardener  to  engage  in  vegetable  forcing 
at  a  remote  distance  from  the  city.  He  may  have  unusu- 
ally favorable  conditions  for  vegetable  forcing,  such  as  a 


MARKETING  13 

sandy  soil,  protected  location,  abundant  supply  of  pure 
water,  cheap  fuel,  accessible  labor  and  a  good  road  to  the 
city.  Under  such  conditions,  an  auto  truck  may  make 
vegetable  forcing  an  attractive  business  proposition. 

(2)  The  truck  makes  it  possible  to  deliver  produce 
promptly  and  speedily.  This  is  a  great  advantage  when 
a  rush  order  is  received,  or  when  the  market  is  unusually 
brisk  and  it  is  important  to  move  the  crop  as  rapidly  as 
possible.  There  may  be  a  shortage  of  labor  in  the  green- 
houses, and  a  motor  truck  enables  the  salesman  to  spend 
more  hours  in  production  instead  of  in  marketing.  It  is 
also  desirable  for  the  vegetables  to  be  placed  on  the  mar- 
ket as  soon  as  possible  after  they  are  packed.  They 
should  not  be  unnecessarily  exposed  to  either  excessively 
hot  or  very  cold  weather. 


Fig.  59. — A  load  of  cucumbers  en  route  to  shipping  station. 

As  a  source  of  power,  gasoline  may  be  cheaper  than 
oats.  In  other  words,  many  growers  find  that  it  is  more 
economical  to  deliver  with  auto  trucks  than  with  horses 
and  wagons.  Furthermore,  the  auto  truck  may  be  kept 
on  the  road  constantly,  if  necessary,  and  made  to  take  the 
place  of  several  teams. 

Whether  a  motor  truck  or  a  wagon  is  used,  it  should  be 
constructed  so  as  to  protect  the  vegetables  from  extreme 


174  VEGETABLE  FORCING 

cold  while  the  vegetables  are  being  transported  to  market. 

Refrigeration. — When  carloads  of  greenhouse  vege- 
tables are  shipped  to  distant  markets  during  the  months 
of  June  and  July  it  is  necessary  to  ice  the  cars. 

Pre-cooling. — Sometimes  it  is  an  advantage  to  pre-cool 
vegetables  before  they  are  sent  to  market.  An  Ohio 
grower  has  found  a  cold  storage  room  adjoining  the  pack- 
ing room  a  great  advantage.  It  is  commodious,  and  the 
large  double  doors  permit  the  entrance  of  a  loaded  truck. 
During  hot  weather  a  picking  of  tomatoes  may  be  made, 
if  desired,  on  Saturday  afternoon  and  held  in  prime  con- 
dition for  the  Monday  morning  market.  This  cooler  is 
also  valuable  for  the  temporary  storage  and  cooling  of 
crops  grown  out  of  doors. 

Advertising — There  are  numerous  ways  of  advertising 
greenhouse  vegetables.  The  vegetables  themselves,  if 
high  in  quality,  are  the  best  advertisement.  A  neatly 
painted  and  lettered  wagon  or  auto  truck  will  gain  pub- 
licity for  the  grower.  Attractive  brands  and  trademarks, 
placed  on  the  packages  or  wrapping  papers,  are  always 
effective.  It  sometimes  pays  to  place  advertisements  in 
newspapers  which  circulate  in  towns  or  cities  where  the 
vegetables  are  sold.  Gate  bulletins,  if  vegetables  are  sold 
at  the  greenhouse,  will  attract  patrons.  Circulars  or 
letters  sent  to  the  homes  of  prospective  buyers,  giving  in- 
formation relating  to  the  quality  and  wholesomeness  of 
the  vegetables,  should  increase  the  volume  of  business. 

Co-operative  associations  are  not  as  common  as  they 
should  be  among  gardeners  who  are  growing  vegetables 
under  glass.  Some  of  the  Cleveland,  Ohio,  growers  have 
found  it  an  advantage  to  conduct  a  co-operative  sale 
store.  A  strong  organization  has  been  formed  at  Ashta- 
bula,  Ohio. 

An  interesting  organization  has  been  formed  at  Grand 
Rapids,  Mich.  The  organization  consists  of  about  30 
greenhouse  men  who  have  their  goods  sold  for  them 


MARKETING  175 

collectively.  The  selling  is  done  by  a  produce  company 
which  is  also  a  member  of  the  association,  and  whose 
members  are,  in  addition,  general  merchants.  The  com- 
pany receives  for  its  services  a  certain  fixed  price.  The 
greenhouse  men  that  are  in  this  association  raise  practi- 
cally nothing  but  lettuce  and  tomatoes.  The  lettuce  is 
cut  at  the  greenhouses,  and  placed  in  boxes  especially 
prepared  for  same  and  brought  to  the  company's  store, 
where  it  is  inspected,  washed,  packed  and  prepared  for 
shipment.  This  is  done  under  the  supervision  of  the 
association  and  at  the  association's  expense,  2  per  cent 
ot  the  gross  sales  being  taken  out  to  cover  these  ex- 
penses. The  tomatoes  are  handled  in  practically  the 
same  manner,  and  the  aim  of  the  association  is  to  pack 
its  stuff  uniformly,  and  to  see  that  only  vegetables  of 
good  quality  are  put  on  the  market.  It  has  also  been  the 
aim  of  the  association  through  its  selling  agents  to  obtain 
as  wide  a  distribution  of  its  products  as  possible.  The 
association  has  been  remarkably  successful.  While  the 
members  have  full  power  through  their  officers  and  com- 
mittees to  pass  upon  all  questions  concerning  their  goods, 
they  have  always  left  the  selling  of  them  entirely  to  their 
regularly  appointed  agents.  The  lettuce  returns  are  pro- 
rated weekly  and  all  who  bring  the  lettuce  in  one  week 
receive  the  same  price.  The  tomato  sales,  on  account  of 
more  rapid  fluctuation  of  the  market,  are  pro-rated  twice 
weekly. 

There  is  a  unique  organization  of  eight  to  ten  frame 
growers  at  Norfolk,  Va.,  known  as  the  "Hotbed  Growers' 
Association."  Each  member  of  this  association  is  also  a 
member  and  stockholder  of  the  Southern  Produce  Com- 
pany, and  secures  affiliation  in  this  way  with  the  larger 
and  stronger  organization.  The  members  of  the  Hotbed 
Association  plant,  harvest  and  market  the  same  crops  at 
the  same  time.  This  insures  large  shipments,  and  elimi- 
nates, as  far  as  possible,  competition  among  the  members. 


176  VEGETABLE   FORCING 

There  is  one  reliable  house  in  each  important  city  that 
receives  consignments  of  the  Hotbed  Association.  In 
return  for  the  privilege  of  receiving  all  of  the  consign- 
ments, each  commission  house  sends  and  pays  for  a 
private  telegram  reporting  prices  obtained  for  each  ship- 
ment. In  addition  to  this  information,  a  daily  market 
wire  from  each  of  these  houses  is  sent  during  the  ship- 
ping season  to  the  Hotbed  Growers'  Association  through 
the  Southern  Produce  Company.  The  members  of  the 
Hotbed  Growers'  Association  are  very  enthusiastic  con- 
cerning the  benefits  of  the  organization. 

Market  slumps  of  greenhouse  products  sometimes 
occur  because  of  inefficient  distribution.  Many  small 
towns,  and  occasionally  cities,  are  meagerly  supplied  with 
greenhouse  vegetables,  while  other  centers  of  population 
have  a  surplus.  It  is  extremely  difficult  to  avoid  such 
congestion  without  co-operation  among  growers. 
Progress  in  this  direction,  for  various  reasons,  has  not 
been  very  encouraging. 


CHAPTER  XII 

ASPARAGUS 

Importance. — The  forcing  of  asparagus  has  appealed  to 
comparatively  few  American  gardeners.  It  is  generally 
believed  that  it  does  not  offer  special  inducements  as  a 
forcing  crop,  and  undoubtedly  there  are  good  reasons  for 
this  opinion.  Statements  may  be  found  here  and  there, 
in  the  literature  relating  to  the  subject,  that  the  forcing 
of  asparagus  is  profitable,  but  it  is  seldom  one  hears  of  a 
grower  who  claims  that  he  has  made  the  venture  a  finan- 
cial success,  or  that  he  considers  the  crop  especially 
promising  for  forcing.  However,  we  must  recognize  the 
fact  that  asparagus  is  forced  in  a  very  limited  way  by 
market  gardeners  and  private  gardeners,  and  occasionally 
by  the  more  extensive  greenhouse  growers,  so  that  the 
subject  deserves  careful  consideration. 

The  forcing  of  asparagus  in  European  countries,  es- 
pecially in  France  and  England,  is  an  important  commer- 
cial proposition.  But  climatic  and  economic  conditions 
there  are  quite  different,  and  it  is  most  improbable  that 
the  same  methods  employed  in  the  United  States  would 
yield  satisfactory  profits.  The  cost  of  labor  in  this 
country  would  likely  be  more  than  the  gross  returns 
would  justify.  Excellent  transportation  facilities  from 
the  South  and  from  California  enable  those  sections  to 
place  an  early  crop  on  eastern  markets  at  prices  which 
can  scarcely  be  met  when  artificial  heat  must  be  used  to 
force  the  shoots.  However,  many  private  gardeners  are 
always  interested  in  the  forcing  of  asparagus,  and  there 
is  no  reason  why  thousands  of  people  should  not  force 
the  crop  for  the  home  table.  It  is  also  probable  that 
commercial  growers  may  become  more  interested  in  the 

177 


178 


VEGETABLE   FORCING 


crop,    especially    if    we    learn    how    to    force    it    more 
economically  so  that  it  could  be  sold  at  lower  prices. 

Principles  involved. — The  large  fleshy  roots  and  crowns 
of  asparagus  are  shown  in  Fig.  60.  These  contain  suffi- 
cient nourishment  to  make  a  good  cutting  of  shoots 
without  receiving  any  additional  plant  food  from  the  soil. 
That  is,  if  sufficient  heat  and  moisture  are  provided, 
shoots  will  be  produced  for  a  period  of  four  to  six  weeks 
when  the  food  supply  of  the  thick  roots  will  be  exhausted 

and  they  will  be 
of  no  further 
value  for  forc- 
ing or  planting 
in  the  open. 
When  the  roots 
are  forced  in 
the  beds  where 
they  stand,  this 
does  not  nec- 
essarily occur, 
for  cutting  may 
be  discontinued 
before  the 
crowns  are 
completely  ex- 
hausted, and  they  will  then  recuperate  in  a  season,  ready 
to  produce  another  crop.  Roots  which  have  been  dug 
and  moved  to  other  locations  for  forcing  are  invariably 
discarded  at  the  close  of  the  forcing  period. 

There  is  a  difference  of  opinion  among  growers  con- 
cerning the  value  of  fertilizers  applied  to  the  forcing  beds. 
Without  any  leaves  or  chlorophyll  it  would  seem  that  the 
shoots  would  be  unable  to  utilize  any  nutrients  other 
than  those  stored  in  the  roots,  but  some  of  the  largest  and 
most  successful  growers  claim  that  positive  benefits  are 
derived  from  the  application  of  commercial  fertilizers  and 


Fig.  60. — A    large   root   of   asparagus   suitable    for 
forcing  purposes. 


ASPARAGUS  179 

also  stable  manures.  Voorhees  held  the  same  opinion. 
When  the  roots  are  forced  in  beds  which  have  full  light, 
perhaps  there  is  sufficient  chlorophyll  development  on  the 
shoots  to  be  of  some  value  in  the  elaboration  of  plant 
food. 

Light  is  not  essential.  The  beds  may  be  in  total  dark- 
ness, though  subdued  or  diffused  light  is  usually  admitted 
to  the  beds.  If  white  shoots  are  desired  there  should  be 
practically  no  light  unless  the  shoots  are  blanched  by 
means  of  a  6  to  8-inch  covering  of  soil  or  sand  over 
the  beds. 

Varieties. — Any  variety  which  produces  large  shoots  is 
suitable  for  forcing.  Inasmuch  as  the  roots  should  be 
grown  for  four  years  before  they  are  large  enough  for 
forcing,  it  is  important  to  select  a  variety  practically 
immune  from  rust.  Much  has  been  said  about  the  merits 
of  old  varieties,  such  as  Palmetto,  Conover  Colossal  and 
Barr  Mammoth,  but  recently  Reading  Giant,  introduced 
by  the  Asparagus  Experiment  Station  of  Concord,  Mass., 
is  receiving  much  attention  because  of  its  freedom  from 
rust  and  its  vigorous  habit  of  growth.  There  is  no  reason 
why  this  superb  variety,  or  other  equally  good  or  su- 
perior, disease-resistant  varieties,  developed  at  Concord 
or  elsewhere,  should  not  ultimately  replace  the  old,  well- 
known  kinds,  both  for  field  culture  and  forcing. 

Growing  the  roots  or  crowns. — Anyone  who  undertakes 
the  forcing  of  asparagus  should  grow  his  own  roots, 
whether  they  are  to  be  forced  in  permanent  field  beds  or 
removed  to  other  locations  where  artificial  heat  can  be 
provided.  It  is  probable  that  the  forcing  of  this  crop 
would  prove  more  renumerative  if  greater  care  were  exer- 
cised in  growing  the  roots.  In  too  many  instances  they 
are  dug  from  field  plantations  which  are  no  longer  profit- 
able because  of  their  age  or  other  unfavorable  conditions. 
As  a  rule,  the  field  plantations  fail  to  return  satisfactory 
profits  because  the  roots  were  perhaps  inferior  when 


180  VEGETABLE  FORCING 

planted  and  they  have  become  largely  exhausted  by  cut- 
ting year  after  year.  In  all  such  cases  the  roots  lack 
vigor,  and  when  planted  in  the  forcing  bed  produce  small 
shoots  and  light  crops.  The  planting  of  a  few  such  roots 
to  meet  the  demand  of  the  home  table  is  not  objection- 
able, but  when  choice  shoots  are  wanted  for  market  the 
strong,  vigorous  roots  must  be  employed  for  forcing. 

Good  roots,  such  as  the  one  shown  in  Fig.  60,  cannot 
be  grown  except  from  good  seed  selected  from  strong, 
rust-resistant  plants.  Such  seed  is  now  obtainable  from 
specialists.  A  rich  plot  of  ground  should  be  selected  to 
start  the  plants,  well  supplied  with  fine,  rotten  manure 
and  available  plant  food.  The  seed  should  be  sown  as 
early  in  the  spring  as  the  ground  can  be  worked.  If  very 
strong  plants  are  to  be  grown,  it  is  desirable  to  be  liberal 
in  the  space  allowed  for  each  plant.  A  seed  dropped 
every  3  inches  in  the  row,  and  the  rows  16  to  18  inches 
apart,  will  give  each  plant  room  for  its  best  development. 
A  few  radish  seeds  sown  with  the  asparagus  will  germi- 
nate promptly  and  mark  the  rows,  and  thus  facilitate 
cultivation.  The  asparagus  seeds  are  slow  to  germinate 
and  the  plants  will  not  appear  for  about  four  weeks. 
There  should  be  frequent  tillage  throughout  the  summer. 
An  excellent  plan  is  to  cultivate  the  nursery  until  mid- 
summer and  then  apply  a  3-inch  mulch  of  horse  manure 
which  has  been  aerated  a  few  days  by  spreading  it  in  a 
loose  pile  not  more  than  18  inches  deep.  The  manure 
will  prevent  weed  growth  and  conserve  soil  moisture 
more  perfectly  than  tillage,  and  liquid  plant  food  will  be 
furnished  the  asparagus  after  every  rain.  Overhead  irri- 
gation and  manure  mulching  can  be  used  to  advantage  in 
growing  strong  roots.  Top-dressing  a  few  times  during 
the  summer  with  nitrate  of  soda  at  the  rate  of  100  pounds 
to  the  acre  will  prove  beneficial  unless  the  soil  is  very 
fertile.  No  effort  should  be  spared  to  grow  unusually 
strong  roots. 


ASPARAGUS 


181 


An  interesting  experiment  has  been  made  by  Myers 
of  The  Pennsylvania  State  College  to  determine  the  value 
of  crowns  of  different  sizes.  While  the  investigation  was 
made  primarily  for  the  benefit  of  the  trucker  and  market 
gardener,  it  also  contains  valuable  lessons  for  growers 
who  are  engaged  in  the  forcing  of  this  vegetable.  In  the 
spring  of  1908,  one-year  roots  of  Palmetto  were  pur- 
chased and  divided  into  three  grades  or  sizes,  No.  1  being 
the  largest,  No.  2  medium  size,  and  No.  3  the  smallest. 
Two  rows  340  feet  long  were  planted  with  each  grade. 
The  following  graph  (Fig.  61)  shows  in  a  striking 
manner  the  returns  of  each  size  over  a  period  of  six  years. 

-ASPARAGUS- 
SIZE  OF  CROWNS  EXPERIMENT 


VUU>  1110 


viao  mi 


YIELD  1112 


Y!£IDI1IJ       - 


SUMMARY  Of  riELO  OF  P/U.METTO 


Fig.  61. — Graph  showing  returns  from  asparagus  roots  of  different  sizes. 

It  will  be  seen  that  the  smallest  roots  give  the  smallest 
returns  for  every  year,  though  the  difference  is  not  so 
marked  after  the  second  year  of  cutting.  The  difference 
between  returns  of  roots  of  first  and  second  size  is  worth 


182  VEGETABLE  FORCING 

considering  but  is  not  so  striking.  The  experiment 
shows  that  it  is  a  poor  business  proposition  to  plant  small 
roots,  whether  they  are  to  be  used  for  field  culture  or  for 
forcing.  Average  annual  receipts  per  acre,  during  six 
seasons  of  cutting,  from  No.  1  roots  were  $539;  from 
No.  2,  $521 ;  and  from  No.  3,  $418. 

There  is  absolutely  nothing  to  be  gained  by  planting 
more  than  one-year-old  asparagus  roots  in  field  planta- 
tions. If  roots  are  to  be  grown  primarily  for  forcing,  it 
would  seem  that  the  most  profitable  plan  would  be  to 
transplant  the  yearling  roots  early  in  the  spring,  and  to 
set  them  closer  together  than  would  be  desirable  if  the 
beds  were  to  be  cut  over  a  term  of  six  years  or  more. 
Good  plants  and  strong  roots  may  be  grown  when  they 
are  set  in  rows  only  3  feet  apart  and  the  plants  1  foot 
apart  in  the  rows.  Such  close  planting  is  unnecessary,  of 
course,  if  plenty  of  land  is  available.  Somewhat  stronger 
roots  will  probably  be  grown  if  they  are  planted  2  by  4 
feet  apart.  Whatever  planting  distances  are  adopted,  the 
plantation  should  have  thorough  tillage  until  the  roots 
are  dug  for  forcing.  Some  gardeners  prefer  to  begin 
cutting  in  the  field  the  second  season  from  planting.  It 
will  be  seen  by  Fig.  61  that  No.  1  roots,  planted  in  1908, 
produced  $106  worth  of  asparagus  to  the  acre  in  1910. 
In  four  years  of  cutting,  No.  1  roots  produced  a  total  of 
$1,673  worth  to  the  acre,  after  which  they  were  in  prime 
condition  for  digging  and  forcing.  Most  growers  who 
have  had  experience  in  forcing  asparagus  prefer  to  dig 
roots  that  are  four  years  old  from  transplanting.  In  this 
event,  No.  1  roots  would  have  returned  gross  receipts 
amounting  to  only  $397  to  the  acre.  When  roots  are  to 
be  used  for  forcing  it  is  questionable  whether  the  most 
profitable  practice  is  to  dig  them  so  early.  It  will  be  seen 
by  referring  again  to  Fig.  61  that  maximum  returns  were 
not  reached  until  1914,  which  was  the  fifth  cutting  season. 

Digging  and  storing  roots. — Unless  the  crop  is  to  be 


ASPARAGUS  183 

forced  in  the  field  where  the  roots  stand,  it  will  be  neces- 
sary to  dig  the  crowns  late  in  the  fall  before  the  ground 
freezes.  In  most  sections  of  the  North  this  work  should 
be  done  not  later  than  November  10.  There  should  be  as 
little  mutilation  of  the  roots  and  buds  as  possible,  for  any 
damage  to  them  will  necessarily  reduce  their  value  for 
forcing  purposes.  The  grower,  however,  must  not  be 
alarmed  if  he  finds  that  it  is  impossible  to  remove  old 
plants  from  beds  without  breaking  off  many  of  the 
long,  fleshy  roots.  It  was  a  difficult  task  to  dig  the  large 
root  shown  in  Fig.  60,  and  this  is  one  of  the  chief  reasons 
for  using  younger  roots.  Four  and  five-year-old  roots 
may  be  removed  by  plowing  along  both  sides  of  the  row 
and  then  loosening  the  roots  with  a  spading  fork.  The 
expense  of  this  method  of  harvesting  the  roots  is  much 
less  than  that  of  digging  them.  Any  soil  that  naturally 
adheres  to  the  roots  is  allowed  to  remain. 

The  crowns  should  not  be  unnecessarily  exposed  to 
the  wind  and  air,  but  should  be  promptly  stored  where 
they  will  not  dry  out.  A  shed,  cool  cellar,  cave  or  pit 
may  be  used  for  this  purpose.  Sufficient  soil  should  be 
thrown  over  the  roots  to  keep  them  moist. 

Forcing  in  permanent  beds. — Numerous  plans  have 
been  used  for  forcing  asparagus  in  permanent  beds  with- 
out removing  the  roots  to  other  quarters.  It  is  claimed 
by  some  growers  that  this  method  produces  larger  shoots 
of  better  quality  than  can  be  obtained  from  transplanted 
roots.  An  additional  advantage,  as  previously  stated,  is 
that  the  roots  are  not  completely  exhausted  and  may  be 
used  again,  perhaps  several  times,  for  forcing.  While 
the  arguments  seem  to  be  in  favor  of  forcing  the  roots 
where  they  have  been  grown,  we  do  not  know  of  any 
extensive  growers,  though  there  may  be  some,  who  are 
following  this  method. 

The  simplest  plan  of  field  forcing,  sometimes  practiced 
by  amateur  gardeners,  is  to  pile  hot  manure  around  bar- 


184  VEGETABLE  FORCING 

rels  or  small  frames  placed  over  the  asparagus  crowns. 
The  top  of  the  barrel  may  be  covered  with  canvas  or 
boards  to  conserve  the  heat. 

Ordinary  coldframes  placed  over  the  beds  and  covered 
with  glass  sash  will  advance  the  crop  much  earlier  and 
more  rapidly  in  the  spring  than  if  it  is  left  without  cover- 
ing. This  method  is  used  to  some  extent  by  market 
gardeners.  Additional  heat  may  be  furnished  by  banking 
the  frames  with  hot  manure,  or  a  coil  of  steam  or  hot 
water  pipes  may  be  placed  in  the  frame. 

Hot  manure  is  sometimes  placed  over  the  beds  early 
in  the  spring  and  allowed  to  remain  until  the  shoots 
start,  after  which  it  is  removed.  This  method  cannot  be 
used  too  early  in  the  spring  without  taking  risks  of  losses 
from  freezing. 

European  gardeners  and  perhaps  a  few  American 
growers  force  asparagus  by  plowing  or  digging  a  trench 
midway  between  two  rows.  The  soil  is  thrown  over  the 
rows  of  asparagus  and  the  trenches  are  filled  with  hot 
manure.  Sometimes  such  trenches  are  lined  with  brick, 
with  passageways  to  the  asparagus  rows,  thus  making 
them  permanent.  Steam  pipes  may  be  placed  in  the 
tunnels,  with  or  without  manure.  This  plan  does  not 
appeal  to  American  gardeners. 

Whitten,  of  the  Missouri  Station,  conducted  an  interest- 
ing experiment  in  forcing  permanent  beds  by  steaming. 
Trenches  were  made  between  the  rows  and  covered  with 
12-inch  boards  which  rested  on  4-inch  blocks  placed 
along  either  side  of  the  trenches.  This  formed  tunnels 
between  the  rows  through  which  hot  steam  was  con- 
ducted. To  guard  against  the  escaping  of  steam,  2  or  3 
inches  of  soil  was  placed  over  the  boards  and  the  entire 
plantation  was  covered  With  5  or  6  inches  of  horse  ma- 
nure. The  following  data  regarding  the  experiment  are 
quoted  from  Bulletin  43  of  the  Missouri  Station : 

"To  conduct  the  steam  a  1^-inch  pipe  was  carried  above  ground 
from  the  boiler  to  one  end  of  the  central  tunnel,  a  distance  of  185 


ASPARAGUS  185 

feet.  A  steam  hose  long  enough  to  reach  each  tunnel  was  attached 
to  this  pipe  through  which  to  blow  steam  into  the  tunnels.  It  was 
not  the  idea  to  give  a  constant  supply  of  steam,  but  to  discharge  a 
little  into  the  tunnels  each  afternoon,  or  as  often  as  was  necessary 
to  maintain  sufficient  warmth.  A  piece  of  tile  was  inserted  into  the 
mouth  of  each  tunnel  to  prevent  the  discharging  steam  from  tearing 
away  the  earth. 

"The  first  steam  was  turned  into  the  tunnels  on  November  14, 
1896.  Steam  was  discharged  into  each  tunnel,  not  to  exceed  five 
minutes  at  a  time,  in  order  not  to  heat  the  earth  too  hot  in  any 
single  place.  It  required  about  one  hour  of  steaming  the  first  day 
to  bring  the  bed  up  to  the  required  temperature  of  sixty  degrees. 
The  distribution  of  heat  throughout  the  bed  was  very  uniform  and 
satisfactory.  The  moist  steam  seemed  to  permeate  the  soil  equally 
in  all  directions. 

"After  the  first  day,  very  little  steaming  was  necessary  until  the 
asparagus  began  to  be  produced.  On  an  average  the  bed  was  steamed 
about  twice  in  three  days,  and  then  only  for  about  five  minutes  for 
each  tunnel.  The  soil  and  horse  manure  mulch  seemed  to  hold  the 
heat  very  well,  the  frequent  steamings  keeping  up  fermentation  in 
the  mulch. 

"The  first  asparagus  was  cut  November  24,  10  days  after  the 
first  steam  was  applied.  The  stems  were  cut  just  before  they  got 
through  the  soil  and  were  perfectly  bleached.  They  were  as  large 
as  those  ordinarily  produced  during  the  normal  period  of  growth 
in  spring,  and  were  far  more  crisp  and  delicious. 

"Cuttings  of  asparagus  were  made  almost  daily  for  about  a 
month,  when  the  growth  became  somewhat  weak.  The  last  cutting 
was  made  on  December  22.  During  the  month  141  bunches  of  the 
ordinary  market  size  and  weighing  about  one-half  pound  each  were 
cut  from  this  bed  of  25  by  50  feet.  This  was  equivalent  to  300  feet 
of  row  or  100  hills  of  asparagus. 

"The  second  asparagus  bed  was  managed  the  same  as  the  first. 
It  was  steamed  on  December  16,  1896,  and  the  first  asparagus  was 
cut  on  December  30.  The  weather  was  much  colder  at  this  time 
and  a  little  more  steam  was  required.  At  times,  however,  no  steam 
was  applied  for  two  or  three  days,  and  the  temperature  of  the  bed 
did  not  fall  much  below  sixty  degrees.  The  finest  asparagus  was 
produced  during  the  coldest  weather.  The  time  of  cutting,  how- 
ever, was  slightly  more  irregular  than  in  the  previous  bed,  and  was 


186  VEGETABLE  FORCING 

prolonged  until  February  26,  1897.  The  bed  was  25  by  75  feet,  or 
equivalent  to  a  row  450  feet  long.  It  produced  234  market  bunches 
besides  considerable  that  was  taken  for  exhibition  purposes. 

"At  this  writing,  May  2,  1898,  the  spring  growth  of  asparagus 
from  the  beds  forced  during  the  winter  of  1896-97  shows  that  one 
season's  growth,  after  forcing  is  sufficient  for  the  plants  to  regain 
their  normal  vigor. 

"By  blowing  steam  directly  into  the  tunnels  the  soil  is  kept  moist; 
the  steam  has  a  penetrating  effect,  and  permeates  all  parts  of  the 
bed,  giving  a  uniform  heat  throughout;  this  moist  steam  keeps  up 
a  continual  fermentation  of  the  manure  mulch,  thus  giving  heat 
and  only  occasional  brief  steamings  are  necessary. 

"Care  must  be  taken  not  to  use  too  much  steam  at  one  time,  or 
the  plants  may  be  ruined  by  over-heating.  Our  asparagus  rows 
were  4  feet  part,  the  tunnels  midway  between  them  were  only  8 
inches  wide,  and  yet  we  found  that  five  minutes  at  a  time  was  as 
long  as  was  safe  to  force  steam  into  a  single  tunnel. 

"These  experiments  have  been  so  successful  as  to  indicate  that 
anyone  provided  with  a  steam  heating  plant,  could  successfully 
force  asparagus  for  the  markets  in  this  manner." 

Ordinary  drain  tiles  were  also  used  at  the  Missouri  Ex- 
periment Station,  but  they  did  not  give  satisfactory  re- 
sults. Cornell  Station  forced  asparagus  in  a  portable 
pipe-frame  house  covered  with  canvas.  It  was  20  by  50 
feet  in  size.  The  sides  or  walls  were  18  inches  high  and 
the  frame  consisted  of  a  ridge  and  three  pairs  of  rafters. 
With  five  lines  of  steam  pipe,  one  under  the  ridge  and 
two  at  each  side  of  the  house,  no  difficulty  was  experi- 
enced in  forcing  asparagus  during  the  winter  months. 
At  the  close  of  the  forcing  period,  the  canvas  is  removed 
and  the  beds  are  cultivated  for  a  season,  and  they  may 
then  be  used  again  for  forcing. 

Forcing  transplanted  roots. — Roots  may  be  removed 
from  the  field  beds  and  forced  wherever  suitable  condi- 
tions can  be  provided.  Perhaps  the  most  common  plan 
is  to  use  the  space  under  greenhouse  benches  for  this 
purpose.  Side  boards  may  be  placed  along  the  walks  to 
retain  the  soil,  or,  if  preferred,  shallow  trenches  may  be 
dug  to  receive  the  roots. 


ASPARAGUS  187 

Sometimes  the  beds  or  benches  of  the  greenhouse  are 
used  for  forcing  asparagus.  If  there  is  a  good  market 
for  the  product,  it  may  pay  as  well  as  lettuce  or  other 
more  commonly  grown  greenhouse  crops. 

A  Pennsylvania  grower  has  been  highly  successful  in 
forcing  asparagus  in  a  house  which  is  about  20  by  50 
feet  in  size..  Almost  the  entire  structure  is  below  the 
surface  of  the  ground.  That  is,  the  brick  walls  which  are 
about  8  feet  high  extend  less  than  a  foot  above  .the 
ground.  The  roof,  which  slopes  slightly,  is  made  of  glass 
and  sash-bars  which  extend  across  the  entire  width  of  the 
house.  There  are  three  tiers  of  beds  in  this  structure  ar- 
ranged in  the  same  manner  as  for  the  culture  of  mush- 
rooms. It  is  seen  at  once  that  the  house  is  economical  in 
construction  as  well  as  in  heating.  The  few  heating  pipes 
needed  are  connected  with  the  furnace  of  the  residence. 
Several  crops  may  be  grown  in  this  house  during  the 
winter.  The  owner  is  well  pleased  with  the  results. 

Sheds  in  connection  with  greenhouses  or  potting  rooms 
are  often  used  for  the  forcing  of  asparagus.  It  may  also 
be  grown  in  cellars  which  are  warm  enough.  A  common 
plan  in  this  country  and  in  Europe  is  to  use  either  manure 
or  steam-heated  frames  or  hotbeds.  When  manure  is 
used,  the  roots  must  not  be  planted  until  the  violent  heat 
has  subsided,  or  small,  spindling  shoots  will  be  produced. 
If  the  climate  is  severe  and  the  roots  are  forced  during 
the  winter  months,  there  should  be  a  depth  in  the  hotbed 
of  not  less  than  30  inches  of  manure. 

Soil. — Any  fine  soil  that  contains  a  large  proportion  of 
organic  matter  will  be  suitable  for  forcing  this  crop.  It 
is  possible  that  nearly  as  good  results  might  be  obtained 
by  planting  in  sand  or  coal  ashes.  If  the  roots  obtain 
even  a  small  percentage  of  nutrients  from  the  earth  dur- 
ing the  period  of  forcing,  then  it  would  be  desirable,  of 
course,  to  use  rich  soil.  Inasmuch  as  this  seems  to  be 
a  debatable  question,  the  safe  practice  is  to  use  fertile 
soil  that  will  absorb  water  promptly  after  its  application. 


188  VEGETABLE  FORCING 

Planting. — Freezing  the  roots  for  a  few  days  before 
they  are  planted  is  thought  to  be  an  advantage.  Pre- 
paratory to  planting,  regardless  of  the  location,  about  2 
inches  of  earth  should  be  placed  in  the  bottom  of  the  beds. 
The  roots,  which  should  not  be  less  than  four  years  of 
age,  are  then  placed  on  this  layer  of  soil  as  close  to- 
gether as  possible  and  the  spaces  around  and  between 
them  rilled  with  soil.  An  inch  or  two  of  earth  is  placed 
orer  the  tops  of  the  crowns,  and  6  to  8  inches  of  soil  is 
used  in  this  way  if  blanched  shoots  are  to  be  grown.  In 
order  to  have  a  succession  of  shoots  it  is  necessary  to 
make  new  plantings  at  intervals  of  three  to  four  weeks. 

There  is  a  better  market  for  forced  asparagus  during 
the  late  fall  and  winter  than  in  the  spring,  when  there 
is  more  competition  from  California  and  the  South.  There 
are  probably  no  better  seasons  to  have  it  ready  for  market 
than  at  Thanksgiving  and  Christmas.  Less  heat  is  re- 
quired, too,  early  in  the  winter  than  during  January  and 
February. 

Temperature. — There  is  some  difference  of  opinion 
concerning  the  most  suitable  temperatures  for  the  forcing 
of  asparagus.  Growers  and  writers  all  agree  that  the 
crop  should  be  started  at  a  low  temperature.  It  will  be- 
gin to  force  at  45  degrees  or  even  below  that  point.  If 
the  temperature  does  not  exceed  50  degrees  for  a  week 
the  results  will  be  better.  High  temperatures  at  first  ap- 
parently produce  weak,  spindling  shoots.  After  strong 
shoots  have  started,  a  temperature  of  55  to  60  degrees 
will  be  satisfactory,  though  some  practical  growers  prefer 
75  degrees  or  even  higher  temperatures. 

Watering. — Immediately  after  the  beds  are  planted 
they  should  be  given  a  thorough  watering.  Enough 
water  should  be  applied  to  penetrate  the  entire  depth  of 
the  beds.  They  should  then  be  kept  constantly  moist, 
and  this  may  require  two  or  three  waterings  a  week. 
Rather  profuse  watering  is  regarded  as  necessary  for  high 
yields  of  large  shoots. 


ASPARAGUS  189 

Marketing. — The  spears  should  be  removed  from  the 
crowns  with  care,  to  avoid  injury  to  buds  or  shoots  that 
may  be  starting.  In  loose  soil  it  is  an  easy  matter  to 
break  them  off  with  the  thumb  and  fingers.  In  deep  beds, 
which  are  required  to  blanch  the  spears,  an  asparagus 
knife  will  be  found  to  be  an  advantage. 

Half-pound  bunches  rather  than  larger  sizes  are  in  most 
demand.  The  price  varies  from  20  cents  to  75  cents  a 
bunch.  It  is  probable  that  satisfactory  returns  cannot  be 
realized  at  a  price  which  is  much  less  than  75  cents  a 
bunch. 

Well-managed  beds  will  yield  for  a  period  of  four  to 
six  weeks.  If  excessively  high  temperatures  are  main- 
tained the  crowns  become  exhausted  in  four  weeks  or  less. 


CHAPTER  XIII 
RHUBARB 

The  forcing  of  rhubarb  is  similar  in  many  respects  to 
the  forcing  of  asparagus,  which  has  been  treated  in  Chap- 
ter XII.  There  are  essential  differences,  however,  that 
make  a  separate  discussion  necessary. 

Importance. — The  forcing  of  rhubarb  is  much  more  gen- 
eral and  extensive  than  the  forcing  of  asparagus.  There 
are  many  large  houses  devoted  to  this  purpose,  and 
hundreds  of  truckers,  market  gardeners  and  even  farmers 
find  it  profitable  to  grow  more  or  less  rhubarb  when  out- 
of-door  plants  are  not  producing. 

The  growing  of  rhubarb  in  cellars  and  basements  for 
the  home  table  and  perhaps  a  small  surplus  for  market  is 
particularly  satisfactory.  Just  a  little  nook  or  corner  will 
grow  all  that  a  family  can  use.  The  plants  themselves, 
grown  in  subdued  light,  are  very  beautiful  and  their 
aesthetic  value  appeals  to  the  amateur. 

Quality. — The  city  consumer  as  well  as  the  gardener 
who  supplies  his  own  table  soon  discovers  that  forced 
rhubarb  is  superior  in  quality  to  that  grown  in  the  open 
where  the  plants  receive  full  light.  The  forcing  of  this 
crop  is  nearly  always  conducted  in  partial  darkness,  but 
sometimes  all  light  is  excluded.  Whether  grown  in  total 
darkness  or  in  partial  light,  the  quality  is  materially 
affected.  In  texture  the  forced  stalks  are  unusually  crisp 
and  tender  on  account  of  the  development  of  less  woody 
fiber.  The  skin  is  very  thin  and  tender  and  does  not 
separate  readily  from  the  stems.  Rhubarb  forced  in 
partial  light  contains  8  to  10  per  cent  more  water  than 
that  grown  out  of  doors  in  full  light,  so  that  the  proportion 
of  acid  is  less  than  when  the  stalks  are  grown  in  the  open, 

190 


RHUBARB  191 

consequently  less  sugar  is  required  to  sweeten  the  sauce, 
which  is  a  beautiful,  nearly  transparent  pink. 

Light. — Formerly  it  was  the  customary  practice  to 
force  rhubarb  in  total  darkness.  Total  darkness  prevents 
the  development  of  chlorophyll;  consequently  the  stalks 
are  whitish  and  the  leaf  blades  mere  rudiments.  The 
markets  show  a  preference  for  a  little  color  in  the  stalks 
and  for  leaf  blades  that  are  slightly  developed  (Fig.  62). 
When  grown  in  diffused  light,  the  stalks  vary  in  shades 
of  pink,  and  some  leaf-blade  development  adds  to  the  at- 
tractiveness of  the  product.  The  stems  average  longer 
than  those  grown  in  total  darkness,  and  some  light  is  an 
advantage  in  caring  for  the  beds  and  in  harvesting  the 
crop. 

The  importance  of  diffused  light  should  be  emphasized. 
Results  will  not  be  satisfactory  if  some  windows  are 
covered  and  others  admit  full  light.  Under  such  condi- 
tions the  growth  will  be  unequal  and  crooked  stems  will 
be  developed  by  the  tops  of  the  plants  bending  toward 
the  light.  Diffused  light  may  be  obtained  by  placing 
brown  paper  over  all  of  the  cellar  windows,  or  burlap 
along  the  sides  of  the  beds,  if  the  crop  is  being  forced 
under  greenhouse  benches. 

Principles. — The  large,  fleshy  leaves  of  the  rhubarb, 
which  is  a  perennial,  elaborate  more  food  than  can  be 
utilized  by  the  parts  of  the  plant  above  ground,  with  the 
result  that  there  is  an  unusual  accumulation  of  nutrients 
in  the  fleshy  roots.  An  old  root  of  a  single  plant  may 
weigh  several  pounds.  When  the  crowns  are  forced 
under  favorable  conditions  of  heat  and  moisture,  the 
supply  of  food  in  the  roots  is  transformed  and  extended 
into  new  growth.  In  other  words,  it  is  transferred  to  the 
leaf  stalks  and  small  leaf  blades.  As  the  stalks  are  har- 
vested, additional  shoots  appear  and  grow  until  the  supply 
of  plant  food  in  the  roots  is  exhausted,  when,  of  course, 
no  further  growth  can  take  place.  If  the  roots  which  are 


192 


VEGETABLE  FORCING 


being  forced  are  wanted  for  propagation,  as  is  sometimes 
the  case,  they  must  be  lifted  from  the  beds  before  they 
are  completely  exhausted,  and  stored  in  a  cool,  moist 
place  until  wanted  for  planting  in  the  field  or  garden. 

Forcing  in  permanent  beds. — Rhubarb  may  be  forced 
in  the  beds  where  the  plants  stand  by  using  practically 
the  same  methods  as  those  used  for  asparagus,  explained 
in  Chapter  XII. 

The  placing  of  barrels  over  hills  is  a  favorite  practice 
among  home  gardeners,  and  this  plan  is  used  to  some 
extent  by  commercial  growers.  Sometimes  a  shallow 

trench  is  dug  around  the 
hill  so  that  the  barrel 
will  stand  a  few  inches 
below  the  surface  of  the 
ground.  No  other  pro- 
tection may  be  given  the 
plant,  but  if  rapid 
growth  is  desired,  hot 
manure  must  be  piled 
and  packed  around  the 
outside  of  the  barrel,  and 
the  latter  covered  with 
boards  if  maximum  heat 
is  required.  Barrels  are 
used  in  this  way  in  the 
spring  of  the  year  when 
there  is  no  further  dan- 
ger of  hard,  freezing 
weather.  The  method  is 
most  suitable  for  home 
gardens. 

Market  gardeners 
sometimes  grow  special 
beds  of  rhubarb  to  be 
used  for  forcing,  and 


Fig.  62. — Rhubarb      stalks      grown      from 
roots   planted   in  coal   ashes. 


RHUBARB 


193 


deep  coldframes  are  then  placed  over  them.  The  plant- 
ing distances  must  be  such  as  to  best  utilize  space  in  the 
frames.  If  the  frames  are  6  feet  wide,  there  may  be 
three  rows  of  plants  running  lengthwise  in  them,  and  the 
plants  may  be  2  feet  apart  or  even  less  than  that  if  the 
beds  are  given  special  care  previous  to  the  forcing  period, 
so  that  they  will  grow  strong  roots. 

Trenches  heated  by  steam  or  hot  manure,  as  explained 
on  page  184,  may  also  be  used,  but  it  is  doubtful  whether 
the  plan  is  practicable  when  labor  costs  as  much  as  it 
does  in  the  United  States. 

In  the  Boston  district,  cheap  permanent  benches  are 
built  over  the  rhubarb  plantations,  where  the  plants  are 
set  about  2  feet  apart  each  way.  Such  houses  ordinarily 
contain  board  walls.  There  are  wooden  rafters  to  sup- 
port hotbed  sash,  placed  to  make  either  an  even-span  or  a 
shed  form  of  roof.  For  use  in  winter,  a  few  coils  of  steam 
or  hot  water  pipes  are  installed  for  the  maintenance  of 
proper  temperature.  For  use  early  in  the  spring,  no  heat 
will  be  required  in  addition  to  that  supplied  by  the  rays 
of  the  sun  on  the  glass  sash.  At  the  close  of  the  period 


Fig.  63. — Rhubarb  growing  in  coal   ashes  in  an  ordinary  cellar. 


194  VEGETABLE  FORCING 

of  forcing,  the  sash  are  removed  and  the  plantation  is 
fertilized  and  cultivated  so  that  the  roots  will  become 
large  enough  to  be  forced  again  the  following  season. 

Portable,  cheaply  constructed  houses  are  sometimes 
used  in  the  forcing  of  rhubarb.  Such  houses  may  be 
moved  from  place  to  place  in  the  field,  whenever  the  roots 
fail  to  yield  satisfactory  cuttings. 

Forcing  transplanted  roots. — The  more  general  practice 
is  to  transplant  the  roots  to  suitable  places  for  forcing. 

A  common  plan  is  to  use  the  cellar  or  basement  of  the 
residence.  Fig.  63  shows  a  small  bed  which  the  writer 
grew  near  the  hot  water  furnace  in  the  cellar.  It  re- 
quired very  little  attention  and  produced  more  rhubarb 
during  the  period  of  production  than  could  be  used  on  the 
home  table.  There  is  no  reason  why  thousands  of  cellars 
should  not  produce,  with  scarcely  any  trouble,  a  delicious 
supply  of  rhubarb  that  would  be  available  from  No- 
vember until  April  or  May,  when  cuttings  can  be  made 
from  plants  in  the  field  or  garden. 

It  is  a  simple  matter  to  grow  rhubarb  in  deep  cold- 
frames  (as  seen  in  Fig.  64).  They  should  be  excavated 
to  a  depth  of  about  2  feet  in  order  to  allow  ample  space 
for  the  growth  of  the  stems.  The  roots  are  planted  close 
together  in  the  bottom  of  the  pits  and  glass  is  placed  on 
the  frames.  This  method  of  forcing  is  satisfactory  when 
the  beds  are  started  any  time  after  the  first  of  March,  or 
perhaps  earlier  in  some  parts  of  the  North.  More  rapid 
growth  will  be  secured  if  hot  manure  is  banked  around 
the  outside  of  the  frame,  or  a  coil  of  pipe  for  the  use  of 
steam  or  hot  water  is  placed  inside  of  the  frame.  Some- 
times the  roots  are  planted  in  the  fall  inside  of  high 
frames  placed  on  the  surface  of  the  ground.  The  roots 
freeze  when  the  weather  gets  cold,  and  later  they  are 
forced  by  placing  sash  on  the  frames  and  banking  them 
with  horse  manure.  This  is  a  practical  commercial 
proposition. 


RHUBARB 


195 


As  previously  stated,  a  common  plan  is  to  utilize  space 
under  greenhouse  benches  for  the  forcing  of  rhubarb. 
The  success  of  this  plan  will  be  determined  largely  by 
the  temperature  which  must  be  maintained  for  other 
crops  in  the  house.  See  page  163.  Occasionally  the  beds 
or  benches  are  used  for  rhubarb,  but  that  space  is  re- 
garded as  more  valuable  for  other  crops  which  require 
more  exacting  conditions  of  heat,  light  and  moisture. 

Manure  hotbeds  are  largely  employed  by  market  gar- 
deners for  this  purpose.  It  is  not  necessary  to  have  a 


Fig.   64. — Rhubarb    growing    in    coldframe. 

depth  of  more  than  18  inches  to  2  feet  of  manure,  unless 
the  climate  is  very  severe.  In  mild  sections  a  foot  of  hot 
manure  will  be  adequate  to  force  the  crop.  Pits,  caves 
and  cellars  of  various  descriptions  are  used.  Small  pits 
and  cellars  are  sometimes  heated  with  lamps  or  stoves. 
Steam  or  hot  water,  however,  is  always  preferable, 
though  good  results  may  be  had  with  stoves. 

There  are  many  cheaply  constructed,  commercial 
rhubarb  houses.  (Fig.  66.)  Sometimes  these  struc- 
tures are  several  hundred  feet  long  and  15  feet  or 
more  in  width.  They  may  be  built  as  sheds  along  the 


196  VEGETABLE  FORCING 

side  of  a  greenhouse  or  other  building.  Economy  in  con- 
struction and  heating  is  important.  Paper  roofs  will  be 
satisfactory  and  second-grade  lumber  may  be  used  for 
the  walls.  Small  windows  should  be  well  distributed  in 
order  that  all  parts  of  the  house  may  be  equally  lighted. 
Such  houses  are  sometimes  used  for  the  storage  of  celery 
and  root  crops  until  Thanksgiving  or  later,  and  the  rhu- 
barb may  be  planted  any  time  after  this,  though  it  is 
seldom  forced  before  January  1. 


Fig.  65. — An    inexpensive   rhubarb    house   near   Boston.      Sash    are   placed    on    the 
frame  whenever  it  is  desired  to  force  the  crop. 

Varieties. — Several  varieties,  such  as  Linnaeus,  Straw- 
berry, Victoria,  Paragon  and  Mammoth,  are  mentioned 
in  connection  with  the  forcing  of  rhubarb.  Varietal  dis- 
tinctions are  not  marked  or  well  defined,  so  that  it  is 
impossible  to  give  specific  information  on  this  subject. 
The  Linnaeus  type  is  earlier  and  smaller  than  the  Vic- 
toria, which  seems  to  be  regarded  as  the  most  vigorous 
of  the  varieties,  excepting,  perhaps,  the  Mammoth.  Both 
Linnaeus  and  Victoria  are  extensively  used  for  forcing. 
There  is  so  much  variation,  however,  in  strains  of  differ- 
ent varieties  that  the  whole  matter  is  in  a  state  of  con- 


RHUBARB  197 

fusion.  Whatever  strain  or  variety  is  used,  the  ideal 
plant  for  forcing  is  one  which  is  vigorous  in  growth  and 
which  produces  a  moderate  number  of  large,  pink  stalks 
rather  than  many  small  ones.  Plants  grown  from  seed 
of  the  same  plant  are  extremely  variable.  If  the  best 
plants  from  a  large  number  of  seedlings  were  selected 
and  multiplied  from  year  to  year  by  the  division  of  the 
roots,  superior  plants  would  soon  be  available  for 
forcing  purposes. 


Fig.  66. — A  simple   house   in  Maryland  for  the  forcing  of  rhubarb. 

Growing  roots. — Rhubarb  is  generally  forced  from 
roots  taken  from  plantations  which  have  produced 
several  crops.  The  stems  of  plants  which  are  four  or  five 
years  old  are  much  smaller  than  those  on  two  and  three- 
year  roots.  When  old  roots  are  used  for  forcing,  the 
stems  are  necessarily  smaller  than  is  preferred  by  the 
market,  but  inasmuch  as  the  old  plantation  is  no  longer 
satisfactory  the  gardener  concludes  that  it  is  better  to 
force  the  crown,  and  thus  make  an  additional  profit,  than 
to  plow  the  field  and  not  attempt  to  save  the  roots.  For 
example,  while  a  superior  forced  product  may  be  ob- 
tained from  three-year-old  roots  (Fig.  67),  the  better 
business  proposition  may  be  to  use  the  roots  in  the  field 
until  they  fail  to  make  a  good  financial  showing  and  then 
force  them,  excepting,  of  course,  the  buds  that  are  neces- 


198 


VEGETABLE  FORCING 


sary  to  make  a  new  planting.     At  any  rate,  this  is  the 
policy  followed  by  most  gardeners. 

Some  interesting  experiments  have  been  made  on  the 
growing  of  forcing  roots  from  seed.  The  Wisconsin 
Experiment  Station  obtained  good  results  from  sowings 
made  broadcast  in  August.  The  seedlings  were  trans- 
planted into  rich  soil  the  following  spring,  when  they 
made  roots  large  enough  for  forcing  in  one  year. 


Fig.  67. — A   large    rhubarb   root   suitable    for   forcing. 

Lazenby,  of  the  Ohio  State  University,  found  that  seed 
sown  about  April  1,  in  very  rich,  moist,  sandy  loam,  pro- 
duced plants  of  forcing  size  in  one  season.  The  rows 
were  2  feet  apart  and  the  plants  thinned  to  15  inches  and 
given  the  most  careful  attention.  By  August  15  some  of 
the  stems  were  20  inches  long  and  the  leaf  blades  a  foot 


RHUBARB  199 

wide.  Single  roots,  dug  in  the  fall,  weighed,  with  the 
little  soil  that  naturally  adhered,  from  two  to  five  pounds 
and  produced  most  excellent  results  in  the  forcing  bed. 
See  page  202  for  notes  on  yields  from  these  roots. 

Seedlings  may  also  be  started  under  glass  and  planted 
in  the  open  the  latter  part  of  April.  If  there  is  danger  of 
frost,  the  young  plants  should  be  well  hardened  before 
they  are  set  in  the  open  ground.  They  stand  transplant- 
ing well,  and  if  started  under  glass  the  total  period  of 
growth  the  first  year  is  very  much  lengthened,  which  is 
a  great  advantage  in  growing  large  roots.  A  soil  of  high 
fertility,  and  the  most  thorough  tillage,  are  absolutely 
necessary  for  the  growing  of  large  roots  in  one  season. 

Digging  and  storing  roots. — The  roots  are  dug  or 
plowed  out  and  stored  in  the  same  manner  as  asparagus 
roots.  See  page  182. 

Preparing  beds. — Beds  which  are  properly  prepared  for 
the  forcing  of  asparagus  are  equally  suitable  for  rhubarb. 
See  pages  183,  186. 

Freezing  roots. — The  growth  of  rhubarb  under  arti- 
ficial conditions  is  accelerated  by  thoroughly  freezing  the 
roots  and  giving  them  a  rest  period  before  they  are 
planted.  Sometimes  they  are  frozen  in  the  field  where 
they  are  plowed  out,  or  they  may  be  exposed  to  hard 
freezing  at  any  time  during  the  winter.  They  should  be 
frozen  solid  throughout.  There  is  no  danger  of  injuring 
them  by  the  lowest  winter  temperatures.  It  is  undesir- 
able, however,  to  leave  the  roots  uncovered  in  the  open 
ground  more  than  several  days,  because  their  vitality  will 
then  be  reduced  by  excessive  loss  of  moisture.  One  to 
three  days  of  freezing  will  have  the  desired  effect.  In 
mild  climates  where  there  is  no  hard  freezing,  drying 
the  roots  for  a  short  time  has  much  the  same  effect  as 
freezing  them,  though  drying  should  be  avoided  if 
possible  because  it  reduces  their  vitality.  An  excellent 
plan  is  to  dry  the  roots  for  a  day  and  then  pile  them  in  an 


200  VEGETABLE  FORCING 

open  shed,  where  they  are  covered  with  straw  or  other 
litter.  When  cold  weather  arrives,  uncover  the  roots 
and  freeze  them  preparatory  to  planting. 

Planting. — The  roots  are  placed  close  together  on  a  bed 
of  soil  2  or  3  inches  deep.  Care  should  be  exercised  that 
all  spaces  between  the  roots  are  filled  and  the  roots  them- 
selves covered  with  2  or  3  inches  of  soil.  The  small  bed 
of  plants  shown  in  Fig.  63  was  grown  in  hard  coal  ashes. 
We  have  had  just  as  good  results  with  small  lots  in  soft 
coal  ashes.  It  would  seem  that  any  medium,  such  as  soil, 
ashes,  moss  or  sawdust,  which  would  hold  moisture  for 
the  roots,  would  be  satisfactory  for  forcing  rhubarb.  In 
large  cellars  or  buildings,  narrow  passageways  or  walks 
should  be  left  about  every  5  feet  for  convenience  in  har- 
vesting the  crop.  When  a  succession  of  stalks  is  desired, 
new  roots  should  be  started  at  intervals  of  about  a  month, 
depending  on  the  rapidity  with  which  the  crop  is  forced. 
There  is  less  breakage  and  mutilation  of  the  roots  if  they 
are  handled  and  planted  while  in  a  frozen  condition. 

Watering. — A  thorough  watering  is  given  the  beds  im- 
mediately after  they  are  planted.  The  amount  and  fre- 
quency of  the  applications,  thereafter,  will  depend  mainly 
on  the  method  of  heating  and  the  location  of  the  beds 
with  regard  to  rapidity  of  evaporation.  Ordinarily,  the 
beds  do  not  need  to  be  watered  oftener  than  once  or  twice 
a  month.  They  should  be  kept  moist,  but  over-watering 
may  be  harmful  by  causing  decay  and  soft  stems. 

Temperature. — Rhubarb  begins  to  grow  at  a  tempera- 
ture slightly  above  freezing.  A  crop  may  be  matured 
when  the  temperature  does  not  at  any  time  rise  above  45 
degrees.  Low  temperatures  are  considered  favorable  to 
high  yields.  Growth  is  very  slow  when  the  temperature 
is  under  50  degrees  and  a  comparatively  long  time  is 
required  to  mature  the  entire  crop.  A  temperature  rang- 
ing from  55  degrees  to  60  degrees  is  ideal  and  that  from 
50  degrees  to  55  degrees  gives  excellent  results.  If  the 


RHUBARB  201 

temperature  ranges  from  55  degrees  to  60  degrees,  stalks 
will  be  large  enough  to  cut  in  about  25  to  30  days  from 
planting,  and  the  beds  will  produce  for  at  least  four 
weeks.  Excessively  high  temperatures  not  only  cause 
rapid  growth,  but  the  stalks  will  be  spindling. 

Harvesting  and  marketing. — The  brittle,  tender  stalks 
must  be  handled  with  extreme  care  to  avoid  injury.  They 
are  easily  removed  from  the  crowns  by  grasping  the  base  of 
the  stalk  with  the  hand,  and  with  the  index  finger  of  the 
same  hand  breaking  and  pulling  the  stalk  from  the  crown 
without  damaging  those  that  may  be  starting.  The 
stalks  should  be  removed  as  soon  as  they  have  attained 
marketable  size.  If  left  too  long  they  become  soft, 
spongy  and  unsalable.  Washing  the  stems  is  not  con- 
sidered desirable  because  they  keep  in  better  condition 


Fig.  68. — Rhubarb   forced   in  total   darkness.     Note   small   leaf  blades. 

for  a  longer  period  if  no  water  is  used.    A  cloth  or  brush 
will  remove  any  soil  that  may  adhere  to  the  stalks. 

The  number  of  stems  which  should  be  tied  in  a  bundle 
will  depend  on  their  size.  If  they  are  large,  three  or  four 
(as  shown  in  Fig.  68)  will  be  sufficient.  If  small,  twice 
that  number  may  be  required. 


202  VEGETABLE  FORCING 

Forced  rhubarb  for  market  is  usually  tied  with  red  tape. 
Some  growers  prefer  white  tape.  A  common  practice  is 
to  tie  a  dozen  bunches  into  one  bundle  and  then  sell  by 
the  dozen.  Oiled  paper  can  be  used  to  advantage  in 
wrapping  the  bundles  or  even  the  individual  bunches. 

Yields  and  returns  are  extremely  variable.  The  small 
patch  2  feet  square  (shown  in  Fig.  63),  grown  in  coal 
ashes,  was  planted  January  9.  The  cellar  was  a  little 
cool  for  rapid  growth. 

The  bed  of  4  square  feet  produced  as  follows : 

February  24 33  ounces 

March  1   42  ounces 

March  4  39  ounces 

March  9   129  ounces 

March  25   50  ounces 

This  makes  a  total  of  about  18  pounds,  or  4^  pounds 
to  the  square  foot.  The  six  stalks  shown  in  Fig.  62 
weighed  22  ounces.  Their  height  ranged  from  15  to  18 
inches,  and  the  largest  were  an  inch  in  diameter.  This 
bed  was  located  about  4  feet  from  a  hot  water  furnace. 

The  Market  Growers'  Journal  reports  the  following 
weights  and  measures  relating  to  10  selected  stalks  grown 
by  Lazenby  from  one-year  roots  at  the  Ohio  State 
University : 

Inches 

Average  length  of  stem . 17.3 

Average  length  of  leaf  blade 4.4 

Total  length  of  leaf 21.7 

Average  length  of  leaf  blade 3.0 

Average  weight  of  whole  stalk 4.6 

The  crop  sold  from  one  lot  of  roots  in  an  8  by  10  foot 
bed  in  the  cellar  brought  $10.  Two  crops  from  seedling 
roots  grown  on  185  square  feet  of  space  sold  for  $35. 

In  "The  New  Rhubarb  Culture/'  Morse  reports  $144 
as  the  winter  returns  from  a  cellar  36  by  54  feet  in  size, 
heated  by  two  large  lamps. 


RHUBARB  203 

Perhaps  an  average  return  for  3  by  6  foot  sash  for 
rhubarb  grown  in  coldframes  is  $1.50  each.     Prices  per_ 
dozen  bunches  range  from  60  cents  to  $1.50.    It  is  some- 
times sold  by  the  pound. 


CHAPTER  XIV 
LETTUCE 

Most  of  the  forced  lettuce  sold  in  the  city  markets 
previous  to  1888  was  grown  almost  exclusively  in  hot- 
beds and  coldframes.  About  this  time  greenhouse  con- 
struction became  active,  and  the  development  of  the 
industry  has  surpassed  the  expectations  of  the  most  opti- 
mistic of  the  pioneer  growers.  W.  W.  Rawson  of  Boston, 
Mass.,  was  the  most  conspicuous  of  the  eastern 
horticulturists  who  were  producing  head  lettuce  in  green- 
houses for  a  number  of  years  previous  to  1890.  Eugene 
Davis  of  Grand  Rapids,  Mich.,  is  the  pioneer  western 
grower.  He  added  to  his  range  from  year  to  year  until 
he  was  one  of  the  most  extensive  growers  in  the  West. 
He  is  the  originator  of  the  Grand  Rapids  lettuce,  and  this 
accomplishment  has  won  for  him  the  distinction  which  he 
so  well  deserves,  for  it  is  practically  the  only  variety 
grown  in  greenhouses  from  central  Pennsylvania  west- 
ward. The  history  of  lettuce  forcing  in  the  United  States 
has  been  closely  associated  with  the  growing  of  other 
crops  under  glass,  particularly  cucumbers  and  tomatoes. 
See  Chapter  I. 

Importance. — Lettuce  is  unquestionably  our  most  im- 
portant vegetable  forcing  crop.  It  is  seldom  that  a  large 
commercial  establishment  attempts  the  forcing  of  other 
crops  without  planting  lettuce  at  some  period  during  the 
season.  In  hundreds  of  ranges  the  usual  custom  is  to 
plant  lettuce  in  the  fall  and  continue  its  culture  until  the 
winter  is  well  advanced,  and  then  to  grow  tomatoes  or 
cucumbers  when  weather  conditions  are  more  favorable. 
Profits  can  generally  be  realized  from  lettuce  throughout 
the  forcing  season,  but  this  cannot  be  said  of  either  the 
tomato  or  cucumber,  except  when  growers  are  unusually 

204 


LETTUCE  205 

skillful  and  markets  are  highly  satisfactory.  Lettuce, 
too,  can  be  grown  and  sold  at  prices  which  all  classes  of 
consumers  are  able  to  pay.  It  is  sometimes  called  "the 
poor  man's  crop,"  in  comparison  with  winter  tomatoes 
and  cucumbers,  which,  in  order  that  a  profit  may  be 
realized,  must  be  sold  at  prices  which  class  them  as  lux- 
uries. This  statement,  of  course,  does  not  apply  to  late 
spring  and  early  summer  greenhouse  vegetables.  The 
demand  for  lettuce  is  at  all  times  so  large  that  it  generally 
forms  the  backbone  of  greenhouse  crop  rotations. 

Again,  lettuce  may  be  forced  in  a  great  variety  of  struc- 
tures. It  appeals  not  only  to  the  greenhouse  man  who 
may  be  farming  acres  under  glass,  but  it  is  equally  popu- 
lar with  the  smaller  frame  growers.  Its  habits  of  growth, 
temperature  requirements,  soil  adaption  and  market  de- 
mands give  it  first  place  among  all  the  crops  which  are 
grown  in  greenhouses,  hotbeds  and  coldframes. 

Quality. — High  quality  in  lettuce  is  essential  to  the 
grower  as  well  as  to  the  consumer.  It  increases  demands, 
and  larger  demands  mean  better  prices.  It  is  urgently 
important  for  every  commercial  grower  to  do  whatever 
is  necessary  to  produce  the  highest  quality.  The  success 
of  the  whole  industry  requires  this  if  satisfactory  profits 
are  to  be  realized. 

But  what  is  quality  and  how  is  it  to  be  obtained?  There 
are  differences  of  opinion  as  to  what  constitutes  quality, 
but  we  are  generally  agreed  on  the  following  points: 

(1)  The  leaves  should  be  crisp,  tender  and  succulent; 

(2)  the  flavor  should  be  sweet  rather  than  bitter;  (3)  the 
heads  should  be  firm,  and  this  is  especially  important 
with  compact  heading  varieties;  (4)  the  heads  should  be 
clean  and  free  from  green  aphis  and  injuries  of  insects  and 
diseases ;  (5)  the  color  should  be  light  green  rather  than 
dark  green. 

High  quality  may  be  obtained  by  growing  the  best 
strains  of  the  best  varieties.  Insufficient  attention  is  given 
to  this  matter.  Moderately  rapid,  continuous  growth  is  a 


206 


VEGETABLE  FORCING 


most  important  factor.  Slow  growth  develops  bitterness 
and  woody  tissues.  The  time  of  harvesting  should  have 
careful  consideration.  Head  lettuce  cut  too  soon  lacks 
firmness  as  well  as  quality,  and  loose-heading  sorts  cut  too 
late  are  coarser  and  they  lack  flavor.  Cleanliness  and 
proper  methods  of  marketing  have  an  important  bearing 
on  the  quality  of  lettuce. 


>. 


Fig.  69. — Head   lettuce   in   the   Boston   district. 

Beds  vs.  benches. — A  general  discussion  of  beds  versus 
benches  will  be  found  on  page  38.  Probably  95  per  cent 
of  the  lettuce  produced  in  the  United  States  is  grown  in 
beds  on  the  ground  instead  of  on  raised  benches.  Just 
as  good  crops  may  be  grown  in  ground  beds  and  at  much 
less  expense,  all  factors  considered,  as  on  benches.  Let- 
tuce does  not  require  bottom  heat  as  much  as  do  some 
other  crops,  though  this  is  an  advantage  in  hastening  its 
maturity.  Sub-irrigation  on  raised  beds  has  proven 
highly  satisfactory,  but  this  method,  for  economic  rea- 
sons, has  not  met  with  favor  among  commercial  growers. 

Ground  beds  may  be  of  any  convenient  width.  They 
are  seldom  less  than  5  feet  and  sometimes  they  are  12  to 
15  feet  wide.  Side  boards  or  walls  to  the  beds  are  some- 
times provided,  as  shown  in  Fig.  69,  or  they  may  be 
absent,  as  shown  in  Fig.  70.  This  is  largely  a  matter  of 


LETTUCE 


207 


preference.  Narrow  cement  walks  between  the  beds, 
for  the  convenience  of  the  workmen,  are  of  greater  im- 
portance than  walls. 

Varieties. — Three  general  classes  of  lettuce  are  used 
for  forcing  purposes,  namely,  cabbage  or  compact-head- 
ing varieties,  loose-heading  varieties  and  Cos  or  Romaine. 


Fig.  70. — Grand  Rapids  lettuce  in  a   large  Middle  West   range. 

Of  the  solid-heading  varieties,  White-Seeded  Tennis 
Ball  or  Boston  Market  (and  its  various  selections)  is  the 
best  known  and  most  largely  cultivated  in  greenhouses. 
It  is  grown  almost  exclusively  in  the  large  ranges  of  the 
Boston  district.  Its  chief  points  of  merit  are  early  ma- 
turity, hardiness,  fine  quality  and  compact  heads  with  a 
small  proportion  of  outside  leaves,  thus  making  it  pos- 
sible to  set  the  plants  closer  together  than  other  larger 
varieties  can  be  planted. 

Improved  Keene,  also  known  as  May  King,  is  the  lead- 
ing variety  in  the  Irondequoit  district  of  New  York.  It 
is  even  smaller  than  Tennis  Ball,  but  does  not  form  such 
a  compact  head.  It  may  be  planted  very  closely  together 
and  still  make  heads  large  enough  to  sell  by  the  dozen  in 
the  Rochester  and  Buffalo  markets.  Salamander  or 
Black-Seeded  Tennis  Ball  is  grown  to  some  extent  in  the 
greenhouses  near  Rochester. 


208 


VEGETABLE  FORCING 


Big  Boston  is  the  leading  variety  for  planting  in  hot- 
beds and  coldframes,  but  it  does  not  give  good  results  in 
greenhouse  culture.  It  is  much  larger  than  White-Seeded 
Tennis  Ball  and  must  have  a  third  more  space  to  permit 
proper  development.  The  leaves  are  coarser  than  those 
of  Tennis  Ball  and  the  plants  are  hardier.  It  is  uni- 
versally selected  for  planting  in  muck  soils  and  is  gen- 
erally grown  in  the  extensive  frame  districts  from  New 
Jersey  southward. 

Hubbard  Market  is  a  hardy,  vigorous  variety,  which  is 
grown  in  frames  to  some  extent. 

There  are  many  varieties  of  the  loose-headed  class,  but 
Grand  Rapids  is  practically  the  only  variety  now  grown 
under  glass.  It  is  a  cross  of  Hanson  and  an  unknown, 
curly  English  variety  developed  by  Eugene  Davis, 
Grand  Rapids,  Mich.  The  plants  are  unusually  vigor- 
ous in  growth  and  not  so  susceptible  to  rot  and  other 
diseases  as  the  compact  heading  varieties,  such  as  Tennis 
Ball.  The  beautiful,  curly  leaves  are  used  largely  for 
garnishing  purposes  as  well  as  for  salads. 

The  Romaine  or  Cos  lettuce  does  not  resemble  either 
of  the  other  two  classes.  The  leaves  are  longer  and  more 


Fig.  71. — Cos  lettuce  on  the  right;  head  lettuce  on  the  left. 


LETTUCE  209 

erect,  as  shown  in  Fig.  71.  When  properly  grown,  they 
are  crisp  and  tender,  and  possess  a  peculiar  piquancy 
which  is  agreeable  to  most  people.  As  people  become 
better  acquainted  with  Cos  lettuce,  the  demand  increases. 
When  the  heads  are  nearly  mature,  the  leaves  are  tied 
together  with  raffia,  which  has  the  effect  of  blanching  the 
interior  leaves"  and  making  them  more  crisp  and  tender. 

Several  varieties  of  Cos  lettuce  are  used  for  forcing. 
Trianon  was  found  most  satisfactory  in  a  test  at  the  New 
Hampshire  Station.  The  heads  were  larger  than  those 
of  other  varieties  and  they  were  also  excellent  in  quality. 

Among  other  varieties  which  are  grown  to  some  extent 
under  glass  may  be  mentioned  Bath,  Express,  Golden 
Yellow  and  Dwarf  White  Heart. 

Cos  lettuce  does  much  better  as  a  forcing  crop  during 
the  fall  and  spring  than  at  midwinter. 

Seed  of  the  highest  quality  is  vital  to  success.  Only 
the  purest  strains  should  be  planted,  and  they  should  be 
maintained  and  improved  if  possible,  by  making  careful 
selections.  Some  of  the  most  successful  greenhouse 
growers  produce  their  own  seed  and  sometimes  a  surplus 
to  sell.  When  seed  production  is  to  be  undertaken  the 
plants  should  be  set  12  to  15  inches  apart  in  the  row  and 
there  should  be  ample  space  between  them — not  less  than 
2  feet — to  permit  the  use  of  wheel  hoes  without  injuring 
the  plants.  The  seed  stalks  should  be  tied  to  stakes  so 
that  they  will  not  be  blown  over  by  the  wind.  As  soon 
as  the  seeds  are  fully  developed,  the  stalks  are  cut  and 
hung  in  a  building  to  dry.  Threshing  is  easily  accom- 
plished by  shaking  and  pounding  the  plants,  and  the  seed 
is  then  cleaned  by  the  use  of  a  small  windmill,  or  by 
throwing  it  up  into  the  air,  over  a  smooth  floor  or  sheet, 
and  allowing  the  wind  to  blow  away  the  chaff. 

Inasmuch  as  lettuce  seed  retains  its  vitality  for  three 
or  four  years,  it  is  unnecessary  to  grow  seed  every  year. 
WThen  purchased,  sufficient  quantity  should  be  obtained 
to  last  two  years  or  more,  and  then  preliminary  tests  may 


210  VEGETABLE  FORCING 

be  made  to  determine  the  merits  of  the  seed.  Germina- 
tion trials  should  be  made  from  time  to  time,  and  the  seed 
may  be  sown  thicker,  if  necessary,  in  order  to  obtain  a 
satisfactory  stand  of  plants. 

Soil. — Most  of  the  large  lettuce-forcing  establishments 
are  located  where  the  soil  contains  considerable  sand, 
and  this  is  especially  true  regarding  greenhouses  devoted 
to  the  culture  of  head  lettuce.  Cos  lettuce  seems  also  to 
require  soil  that  contains  a  fairly  large  percentage  of 
sand.  Grand  Rapids  lettuce  is  grown  with  entire  success 
in  practically  all  classes  of  soils,  including  the  heaviest 
with  the  smallest  proportion  of  sand.  The  general  ad- 
vantages of  sand  for  greenhouse  use  have  been  discussed 
in  Chapters  III  and  V,  and  these  should  be  fully  con- 
sidered in  connection  with  the  selection  and  preparation 
of  soils  for  the  forcing  of  lettuce.  Greater  weight  of 
Grand  Rapids  may  be  obtained  in  heavy  soils,  but,  not- 
withstanding this  fact,  growers  prefer  soils  that  are  not 
too  heavy. 

For  the  production  of  head  lettuce,  the  soil  must  be 
well  aerated.  This  can  be  accomplished  to  a  great  ex- 
tent by  the  liberal  use  of  stable  manure  and  sometimes 
by  mixing  muck  with  the  soil.  Experienced  growers, 
however,  claim  that  one  or  both  of  these  materials  cannot 
entirely  take  the  place  of  sand.  An  open,  porous  soil  is 
essential,  though  it  is  possible  to  make  it  too  light  and 
fluffy. 

Beach  made  some  interesting  experiments  at  the  New 
York  Station;  they  were  reported  in  Bulletin  146.  Soils 
of  various  composition  were  used,  but  reference  will  be 
made  to  only  two.  What  is  referred  to  as  the  Geneva 
clay  loam  contained  3.32  per  cent  fine  gravel,  5.20  per 
cent  coarse  sand,  20.71  per  cent  medium  sand,  43.43  per 
cent  fine  sand,  0.94  per  cent  very  fine  sand,  7.96  per  cent 
silt,  1.64  per  cent  fine  silt  and  9.86  per  cent  clay.  The 
Geneva  sandy  loam  contained  0.51  per  cent  fine  gravel, 
0.69  per  cent  coarse  sand,  9.49  per  cent  medium  sand, 


LETTUCE  211 

77.50  per  cent  fine  sand,  2.44  per  cent  very  fine  sand,  1.60 
per  cent  silt,  1.23  per  cent  fine  silt  and  3.79  per  cent  clay. 
It  will  be  noted  that  the  soil  which  is  called  a  clay  loam 
contained  over  70  per  cent  of  sand  of  all  sizes,  and  that 
the  Geneva  sandy  loam  contained  over  90  per  cent,  which 
was  a  decidedly  sandy  soil.  In  discussing  the  results  with 
head  lettuce  grown  on  these  soils,  Beach  states : 

"A  comparison  of  the  records  of  the  four  crops  might  at  first 
give  the  impression  that  the  different  crops  do  not  agree  very  closely 
as  to  their  results,  but  a  more  careful  study  will  show  that  in  reality 
they  conflict  with  each  other  very  little,  if  at  all.  With  the  first 
crop  there  was  no  marked  difference  in  the  weight  of  the  lettuce  on 
the  different  soils.  With  the  second  crop  the  sand  and  manure  gave 
decidedly  heavier  plants  than  did  the  soils  which  contained  clay 
loam,  but  the  latter  really  gave  superior  lettuce,  for  the  plants  on 
sand  formed  rather  loose  heads,  actually  less  valuable  for  market 
than  the  more  compact  though  somewhat  smaller  lettuce  which  was 
grown  on  the  clay  loam  soils.  With  the  third  crop  the  results  were 
quite  similar  to  those  which  were  found  with  the  second  crop.  With 
the  fourth  crop  the  evidence  was  stronger  than  before  in  favor  of 
the  medium,  heavy  clay  loam  lightened  with  fairly  well-rotted  stable 
manure,  as  the  best  of  the  soil  mixtures  which  were  tried  for  forc- 
ing lettuce.  The  lettuce  which  it  produced  was  not  only  superior  to 
that  which  was  grown  on  the  sandy  soil,  in  texture  of  leaf,  firmness 
of  head  and  general  appearance,  but  it  was  also  heavier." 

Fertilizing. — Lettuce  requires  high  fertility.  Rapidity 
of  growth  and  quality  of  the  product  are  largely  de- 
pendent upon  an  abundance  of  available  plant  food.  There 
should  be  no  doubt  in  the  mind  of  the  grower  as  to 
whether  the  soil  is  as  fertile  as  necessary  to  produce  a 
maximum  crop  of  the  best  quality. 

All  are  agreed  that  stable  manure  should  constitute  the 
chief  fertilizing  material  for  lettuce,  because  it  not  only 
supplies  plant  food,  but  creates  favorable  physical  condi- 
tions in  the  soil.  It  is  believed  by  many  growers  that  if 
sufficient  stable  manure  is  used  to  maintain  proper 
physical  conditions  in  the  soil,  the  food  requirements  of 
the  plants  will  be  fully  met  and  there  will  be  no  necessity 


212  VEGETABLE  FORCING 

for  adding  other  fertilizing  materials.  In  fact,  the  results 
of  hundreds  of  growers  might  be  cited  in  support  of  this 
view. 

It  is  claimed  by  some  growers,  especially  by  those  who 
are  cultivating  light  soils,  that  the  free  and  continued 
use  of  stable  manure  ultimately  makes  the  soil  too  open 
and  porous  for  the  best  results  with  lettuce,  and  that  it 
is  preferable  to  use  less  manure,  and  to  supplement  it  with 
commercial  fertilizers.  This  class  of  growers,  however,  is 
in  the  minority,  though  there  are  some  who  obtain  ex- 
cellent results  from  the  applications  of  commercial  ferti- 
lizers in  connection  with  manure.  Rules  cannot  be  made 
regarding  the  use  of  stable  manures  in  greenhouses  be- 
cause conditions  of  soils,  supply  and  kinds  of  manures 
available,  treatment  of  previous  crops,  kind  of  crop  to 
follow,  etc.,  are  so  variable  that  no  one  treatment  will 
suit  all  conditions. 

The  use  of  commercial  fertilizer  in  growing  lettuce 
under  glass  was  advocated  by  Thorne  of  Wooster,  Ohio. 
He  found  that  a  home  mixture  of  20  pounds  of  nitrate  of 
soda,  60  pounds  acid  phosphate  and  20  pounds  muriate  of 
potash,  applied  in  judicious  amounts  with  moderate 
applications  of  manure,  increased  the  yields. 

Nitrate  of  soda  is  frequently  applied  to  lettuce  under 
glass.  Sometimes  the  crop  does  not  make  as  rapid  growth 
as  is  desired;  then  a  light  application  of  nitrate  of  soda 
may  have  a  very  beneficial  effect.  As  explained  before, 
it  may  be  used  in  liquid  form,  the  plants  even  being 
sprayed  with  a  dilute  solution  that  will  not  burn  them, 
the  solution  to  be  washed  from  the  plants  with  a  spray 
of  pure  water. 

When  nitrate  of  soda  is  mixed  with  the  soil  before  the 
lettuce  is  planted,  one  pound  to  100  square  feet  of  space 
will  be  as  much  as  can  be  used  with  safety  to  the  plants. 

A  practice  which  is  increasing  among  farmers,  and 
there  is  no  reason  why  it  should  not  be  just  as  valuable 
for  greenhouse  vegetable  growers,  is  to  mix  acid  phos- 


LETTUCE  213 

phate  or  perhaps  untreated  phosphatic  rock  with  stable 
manure  at  the  barn  or  as  it  is  thrown  from  the  railroad 
cars. 

Various  forms  of  commercial  fertilizers  are  sometimes 
used  in  the  forcing  of  lettuce.  Greenhouse  plants  are 
easily  injured  by  excessive  applications  of  chemicals, 
such  as  nitrate  of  soda,  acid  phosphate  and  muriate  of 
potash,  and  large  amounts  should  not  be  used  at  any 
time.  Sayre  draws  the  following  conclusions  from  fer- 
tilizer experiments  made  at  the  Indiana  Experiment 
Station : 

"In  regard  to  the  experiments  last  year  which  were  reported  at 
the  meeting  of  the  Society  of  Horticultural  Science,  the  items  of 
principal  interest  were  as  follows :  None  of  the  fertilizer  treatments 
except  manure  were  beneficial,  but  the  manure  plots  were  greatly 
superior  and  indicated  that  manure  was  by  far  the  best  and  most 
economical  fertilizer.  Our  report  was  chiefly  concerned  with  the 
effect  of  various  fertilizers  on  the  nitrogen  content  of  the  plant. 
An  analysis  of  the  plants  shows  that  the  chemical  composition,  at 
least  in  regard  to  nitrogen,  was  appreciably  affected  by  the  fertility 
of  the  soil,  and  could  be  modified  by  the  addition  of  chemical  fer- 
tilizers. The  addition  of  phosphorus  to  the  soil  tended  to  decrease 
the  percentage  of  nitrogen  in  the  plant,  and  the  application  of  nitro- 
gen in  addition  to  phosphorus  tended  to  offset  the  phosphorous  effect 
and  raised  the  nitrogen  content  of  the  plant,  but  there  is  a  definite 
limit  to  which  the  nitrogen  content  can  be  raised.  Nitrogen  alone 
slightly  decreased  the  nitrogen  content  of  the  plant  as  might  be  ex- 
pected from  any  element  added  in  excess.  Nitrogen  unquestionably 
tended  to  promote  leaf  growth,  while  phosphorus  tended  to  hasten 
maturity." 

Most  growers  of  lettuce  apply  lime  to  the  beds  about 
once  a  year.  See  Fig.  72. 

Preparation  of  soil. — The  preparation  of  greenhouse 
soils  has  been  fully  discussed  in  Chapters  V  and  VI. 
Stable  manure  is  generally  applied  for  the  first  crop  in 
the  fall,  and,  if  desired,  additional  amounts  for  subse- 
quent crops.  It  may  be  well  decayed,  though  some 
growers  prefer  fine  manure  that  is  comparatively  fresh. 


214  VEGETABLE  FORCING 

In  the  hard  coal  regions  a  favorite  practice  is  to  use  mule 
manure  from  the  mine  stables.  It  is  fine  in  texture  and 
contains  very  little  straw,  hay  or  other  bedding  material. 


Fig.    72. — Pot    experiment    at   The    Pennsylvania    State    College    showing    the    value 
of  lime  for  lettuce. 

In  the  Boston  district,  the  manure  is  spaded  into  the 
soil  to  a  depth  of  12  to  15  inches  or  more.  This  rather 
laborious  method  is  not  regarded  as  necessary  by  the 
growers  of  Grand  Rapids  lettuce.  A  method  which  is 
becoming  more  common  every  year  is  to  use  plows  and 
harrows,  which  may  be  drawn  with  one  horse.  Planting 
the  houses  in  long  narrow  beds  facilitates  the  use  of 
horses  in  the  preparation  of  the  soil. 

Starting  plants. — The  first  sowing  of  lettuce  for  the  fall 
crop  is  generally  made  early  in  August,  though  some  of 
the  largest  growers  do  not  sow  until  about  August  20. 
Sowings  made  August  20  will  produce  marketable  heads 
by  the  latter  part  of  October  or  November  1.  Lettuce 
maturing  before  that  time  does  not  generally  sell  readily 
because  it  must  compete  with  lettuce  grown  in  the  open. 
In  order  to  have  a  continuous  succession  of  lettuce,  sow- 
ings should  be  made  at  intervals  of  a  week  to  ten  days, 
and  larger  sowings  should  be  made  for  the  lots  which  will 
mature  at  times  when  there  will  be  an  unusual  demand, 
as  at  Thanksgiving  and  Christmas. 


LETTUCE  215 

The  rate  of  growth  of  the  plants  should  be  carefully 
considered  when  making  sowings.  For  example,  the 
seedlings  grow  much  more  rapidly  in  the  fall  and  spring 
than  at  midwinter.  Ordinarily,  the  plants  should  not 
stand  in  the  seed  bed  for  a  period  longer  than  three  weeks. 
In  most  instances  it  is  better  to  prick  them  out  in  about 
ten  days  or  less,  and  then  they  will  be  in  no  danger  of 
becoming  weak  and  spindling  from  being  crowded,  and 
there  will  be  less  danger  of  damping-off. 

It  is  important  to  use  no  more  soil  than  will  barely 
cover  the  seed.  Some  growers  prefer  to  use  no  soil  over 
the  seeds,  but  to  keep  them  moist  with  burlap  until  they 
have  germinated  and  then  the  covering  is  promptly  re- 
moved. This  practice  saves  time  and  produces  excellent 
results.  Others  barely  cover  the  seed  and  are  careful  to 
maintain  uniform  moisture  conditions  in  the  beds  so  that 
germination  will  be  uniform.  The  seed  beds  dry  out  very 
rapidly  during  August  and  the  early  fall  months,  so  that 
some  shade  is  usually  necessary. 

Many  growers  sow  in  solid  beds  or  on  raised  benches 
without  the  use  of  flats.  A  large  number  of  growers, 
however,  employ  flats  because  they  find  them  convenient 
and  they  believe  better  plants  can  be  grown  in  them.  If 
the  transplanting  is  attended  to  promptly,  2,500  to  5,000 
plants  may  be  started  in  a  flat  16  by  24  or  12  by  30  inches 
in  size. 

It  is  doubtful  whether  lettuce  should  ever  be  set  closer 
than  2  by  2  inches  apart  at  the  first  transplanting.  At 
some  seasons  of  the  year  and  under  the  most  favorable 
conditions  the  plants  will  begin  to  crowd  each  other  in 
two  to  three  weeks,  when  they  should  be  transferred  to 
the  permanent  beds.  At  each  sowing  and  transplanting 
an  estimate  should  be  made  of  the  number  of  plants  that 
will  be  needed  to  fill  the  beds  and  to  take  the  place  of 
successive  cuttings.  It  is  better  to  err  on  the  side  of 
having  too  many  than  too  few  plants.  When  there  is  a 
surplus,  the  weaker  may  be  discarded.  This  will  count 


216  VEGETABLE  FORCING 

for  greater  uniformity  for  planting  in  the  beds  and  also 
for  marketing. 

Space  may  be  utilized  more  economically  by  using 
pots,  to  some  extent  at  least,  in  the  starting  of  plants. 
For  example,  instead  of  transferring  plants  from  flats,  in 
which  they  have  been  grown  2  by  2  inches  apart,  to  per- 
manent beds,  another  intermediate  shift  may  be  made  to 
2-inch  or  2^-inch  pots  and  the  pots  plunged  between 
plants  in  the  permanent  beds,  for  about  two  weeks.  This 
plan  is  most  suitable  for  houses  in  which  the  lettuce  is 
set  not  less  than  8  inches  apart  each  way  in  the  per- 
manent beds.  The  pots  should  be  plunged  in  the  soil  up 
to  their  rims,  and  then  they  will  not  dry  out  to  any  con- 
siderable extent.  They  may  be  placed  4  inches  apart  one 
way,  as  shown  in  the  following  diagram,  L  denoting  the 
lettuce  plants  just  set  and  P  the  pots  of  smaller  plants : 


P  P  P  P  P  P  P 

L  P  L  P  L  P  L 


When  this  plan  is  followed,  the  potted  plants,  when 
removed  to  permanent  beds  in  two  weeks  after  the  plung- 
ing, will  produce  marketable  heads,  under  favorable  con- 
ditions, in  four  to  six  weeks,  the  length  of  time  depending 
on  the  amount  of  sunshine.  With  a  week  or  two  of  a 
saving  on  each  crop,  it  will  be  seen  that  this  method 
means  the  gaining  of  an  additional  crop  during  the  winter 
forcing  season.  It  is  some  trouble,  of  course,  and  re- 
quires an  outlay  for  pots  and  labor,  but  as  a  business 
proposition,  it  is  worthy  of  careful  consideration. 

Planting  distances. — There  is  the  widest  range  in  plant- 
ing distances  used  by  different  growers.  Tennis  Ball  is 
generally  planted  8  by  8.  Big  Boston  may  be  grown  at 


LETTUCE  217 

these  distances,  but  it  should  have  more  space  for  proper 
development.  Improved  Keene,  when  sold  by  the  dozen 
heads,  does  not  need  more  space  than  6  by  6,  but  requires 
more  liberal  spacing  if  large  heads  are  desired.  Cos 
lettuce  does  very  well  planted  1  by  1. 

Regarding  Grand  Rapids,  a  well-known  Cleveland 
grower  sets  7  by  9 ;  the  largest  grower  in  Ohio,  9  by  9 ; 
most  Ohio  growers,  8  by  8;  a  Johnstown,  Pa.,  grower, 
7  by  8 ;  an  Erie,  Pa.,  grower,  6  by  8.  The  Ohio  station 
concluded  from  experiments  that,  all  things  considered, 
7^2  by  7^2  is  best.  Occasionally  a  grower,  who  has  a 
demand  for  small  heads  by  the  dozen,  plants  6  by  6. 
When  the  plants  are  sold  by  number  rather  than  by 
weight,  the  tendency  is  to  plant  close  together.  Liberal 
spacing  is  favorable  to  maximum  weight  of  individual 
heads,  but  more  time  is  required  to  mature  the  crop  and 
thus  obtain  the  maximum  weight  from  a  given  area. 
When  total  weight  for  an  entire  season  is  considered,  it 
is  possible  that  8  by  8  or  7  by  9  will  give  larger  yields 
than  any  other  spacing,  though  growers  differ  in  their 
opinions  about  this  matter. 

Hexagonal  planting  is  practiced  in  some  greenhouses. 
This  arrangement,  as  shown  in  the  following  diagram, 
gives  each  plant  an  equal  amount  of  space  on  all  sides, 
and  more  plants  may  be  set  in  a  given  area  than  when 
placed  in  squares. 


XX  XXX 

The  gain  in  this  respect  is  considerable  when  a  large 
range  is  planted.  Close  planting  is  a  disadvantage  in 
requiring  a  larger  number  of  plants.  It  is  surprising  how 
many  more  plants  are  required  to  set  a  bed  7  by  7  than 
8  by  8.  More  space  one  way,  as  when  the  plants  are  set 


218 


VEGETABLE  FORCING 


7  by  9,  is  a  great  advantage  in  facilitating  tillage,  either 
with  a  light  wheel  hoe,  narrow  rakes  or  special  tools. 
Rot  and  other  diseases  are  more  likely  to  cause  serious 
losses  when  the  plants  are  set  close  together,  because  of 
poorer  circulation  of  air. 

Somewhat  more  time  is  required  to  harvest,  trim,  wash 
and  pack  closely  set  plants  from  a  given  area  than  if  they 
were  planted  at  greater  distances.  A  special  market, 
however,  for  small  plants  may  more  than  justify  close 
setting. 


Fig.  73. — Transplanting  board  used   for  setting  lettuce.     Note  large   pegs. 

Planting. — When  a  block  of  lettuce  has  been  cut  and 
marketed,  the  ground  should  be  prepared  and  replanted  at 
once.  A  delay  of  only  one  day,  if  the  plants  are  ready, 
means  some  loss.  Furthermore,  the  young  plants  should 
be  transferred  to  the  new  beds  before  they  have  been 
checked  or  stunted  in  growth.  Continuous  growth  from 
germination  to  harvest  is  essential  to  maximum  yields  of 
the  highest  quality. 

Some  kind  of  a  marker  should  be  used  for  spacing  the 
plants  accurately.  Fig.  73  shows  an  inverted  marker 
used  in  a  very  large  establishment.  It  will  be  noted  that 
there  are  three  rows  of  pegs,  and  the  pegs  are  about  2 
inches  in  diameter.  The  workmen  kneel  on  the  boards 
while  they  are  transplanting,  and  when  the  board  marker 
is  moved  the  holes  are  made  ready  for  three  more  rows  of 


LETTUCE 


219 


plants,  thus  involving  no  extra  labor  for  marking  or 
making  the  holes. 

As  much  soil  as  possible  is  retained  on  the  roots  of  the 
plants,  and  they  are  set  at  about  the  same  depth  as  they 
stood  in  the  flats.  It  is  important  for  the  roots  to  be 
placed  in  an  erect  position,  as  shown  by  the  right  hand 
plant  in  Fig.  74.  The  left  plant  is  dwarfed  in  growth 
because  the  taproot  was  bent  when  set  in  the  bed. 
The  soil  is  pressed  firmly  about  the  roots,  and  the  beds 
are  watered.  A  rapid  workman  will  plant  500  or  more 
plants  an  hour.  Strong,  stocky  plants  will  stand  erect 
after  they  have  been  set  in  the  permanent  beds. 

Watering. — The  merits  of  sub-irrigation  for  lettuce 
were  discussed  on  page  155.  Except  for  the  cost  of  install- 
ing this  system  of  watering,  it  is  ideal  for  lettuce.  Over- 


Fig.  74. — Plants  of  the  same  age.     One  on   left  dwarfed  because  the  taproot  Was 
bent  when    the  plant  was  set   in    the   bed. 


220  VEGETABLE  FORCING 

head  irrigation  for  greenhouse  lettuce  is  practiced  by 
nearly  all  the  large  growers.  The  method  is  economical 
and  efficient.  Supplemental  watering  with  a  hose  may 
be  an  advantage  at  times,  but  practically  all  watering 
should  be  done  by  means  of  overhead  nozzle  lines. 

Lettuce  requires  a  large  amount  of  water.  Probably 
the  tendency  with  this  crop  is  not  to  water  enough  rather 
than  too  much.  The  soil  should  be  well  supplied  with 
moisture  throughout  the  period  of  growth.  When  the 
crop  is  approaching  maturity  and  making  the  most  rapid 
gains  in  weight,  an  enormous  amount  of  water  is  lost  by 
transpiration  from  the  leaves,  especially  during  the  spring 
months  when  there  is  so  much  sunshine.  Heavy  .applica- 
tions of  water,  just  before  the  ground  is  covered  with 
the  plants,  are  usually  of  special  value.  Special  care  must 
be  exercised  in  watering  when  the  beds  are  well  covered 
with  plants,  for  there  is  then  very  little  circulation  of  air 
among  the  plants  and  rot  is  more  likely  to  appear  than 
at  any  previous  time.  For  this  reason,  the  watering 
should  be  done  early  in  the  morning  of  bright  days,  if 
possible,  and  then,  if  the  house  is  properly  ventilated, 
the  water  will  evaporate  from  the  leaves  before  night. 

Temperature. — High  temperatures  are  favorable  to 
rapid  growth,  but  excessive  heat  for  this  crop,  associated 
with  high  humidity,  is  certain  to  cause  weak,  spindling 
plants,  and  it  greatly  increases  the  possibility  of  loss 
from  diseases,  while  low  temperatures  have  the  opposite 
effects.  Low  temperatures,  especially  as  the  crop  ap- 
proaches maturity,  are  favorable  to  maximum  weight 
and  compactness  of  heads.  Nearly  all  growers  allow  10 
degrees  higher  temperature  during  the  day  than  at  night. 

Grand  Rapids  lettuce  may  be  successfully  grown  at  a 
wider  range  of  temperatures  than  either  Cos  or  heading 
varieties.  A  higher  night  temperature  than  45  degrees 
for  head  lettuce  would  not  be  permissible  unless  the 
houses  were  ventilated  all  night.  Many  growers  of  head 


LETTUCE 


221 


lettuce  prefer  40  to  45  degrees  at  night  and  10  to  15  de- 
grees higher  by  day. 

Most  growers  of  Grand  Rapids  lettuce  maintain  higher 
night  temperatures  than  they  did  a  few  years  ago.  For- 
merly, 45  degrees  at  night  and  55  to  60  degrees  by  day 
were  standard  temperatures  among  the  best  gardeners. 
Now,  some  of  the  largest  growers  prefer  48  to  50  degrees 
at  night  and  55  to  60  degrees  by  day.  A  night  tempera- 
ture of  45  degrees  with  high  humidity  and  wet  foliage  is 
likely  to  cause  much  more  damage  than  a  temperature 
of  50  degrees  with  low  humidity  and  dry  foliage.  On 
warm,  sunny  days  during  the  spring,  no  harm  will  be 
caused  by  temperatures  of  75  degrees  or  above,  provided  the 
houses  are  well  ventilated.  It  is  always  important  to  have  a 
definite  understanding  with  the  night  fireman  and  watchman 
concerning  the  temperature  that  should  be  maintained. 


Fig.   75. — The   lettuce   in   this   large    range   is   cultivated   with    a   5-pronged   weeder 
attached   to   a   long   handle. 

Ventilation. — Much  has  been  said  on  previous  pages 
about  the  importance  of  ventilation.  In  lettuce  culture  it 
is  one  of  the  means  of  avoiding  losses  from  the  attacks 
of  fungous  diseases  and  of  producing  the  best,  most  com- 
pact heads.  On  very  cold  or  stormy  days  the  ventilators 
are  not  opened  at  all,  while  in  mild  weather  it  is  not  un- 


222  VEGETABLE  FORCING 

Q 

common  to  leave  the  ventilators  open  all  night,  to  some 
extent  at  least.  A  safe  practice  is  to  ventilate  every  day 
as  much  as  weather  conditions  will  permit. 

Cultivation  in  growing  lettuce  under  glass  may  not  be 
as  important  as  when  the  crop  is  grown  in  the  open, 
though  it  is  unquestionably  beneficial.  One  cultivation, 
in  a  few  days  after  the  beds  are  planted,  to  break  the 
crust  of  the  soil,  may  be  sufficient,  but  additional  tillage 
will  be  valuable,  especially  if  the  soil  contains  much  clay 
or  silt.  The  most  common  practice  is  to  use  hand  weed- 
ers  or  pronged  hoes  in  narrow  beds.  Iron  rakes  reduced 
to  a  width  of  6  or  7  inches  are  satisfactory  for  the  cultiva- 
tion of  wide  beds.  The  tool  shown  in  Fig.  75  consists  of 
a  five-prong  hand  weeder  secured  to  the  end  of  a  long 
handle.  Wheel  hoes  are  employed  in  some  houses  where 
the  rows  are  far  enough  apart  to  permit  their  use. 

Intercropping  is  followed  to  some  extent  in  the  grow- 
ing of  lettuce  under  glass.  The  various  systems  em- 
ployed are  discussed  in  Chapter  XXI. 

Frame  culture. — The  forcing  of  lettuce  in  hotbeds  and 
various  types  of  frames  is  treated  in  Chapter  XXII, 
page  403. 

Pot  culture. — Studies  have  been  made  at  several  agri- 
cultural experiment  stations  to  determine  the  value  and 
feasibility  of  maturing  lettuce  in  pots.  Seedlings  which 
are  three  or  four  weeks  old  are  set  in  2-inch  or  2^-inch 
pots,  and  the  pots  of  large  plants,  as  seen  in  Fig.  76,  are 
then  plunged  at  the  usual  distances  for  planting  into  the 
permanent  beds.  The  rims  of  the  pots  should  be  at  least 
half  an  inch  below  the  surface  of  the  bed. 

The  crop  is  watered  and  cared  for  in  the  usual  manner 
until  the  heads  are  large  enough  to  market.  Then  the 
potted  plants  (Fig.  77)  are  lifted  and  sent  to  market  in 
the  pots,  or  preferably  the  balls  of  earth  and  roots  are 
wrapped  in  paper  and  a  dozen  plants  placed  in  a  flat  or  a 
market  basket.  The  plants  will  hold  up  better  if  the 


LETTUCE  223 

balls  of  earth  are  soaked  with  water  before  they  are  sent 
to  market. 

Experiments  at  the  Tennessee  station  resulted  in  a  15 
per  cent  smaller  yield  by  weight  than  was  obtained  by 


Fig.  76. — Pot-grown  plant  ready  to  set  in  the  bed 

the  usual  method  of  setting  in  beds,  but  a  higher  price 
was  obtained  for  the  pot-grown  lettuce  on  the  Knoxville 
market.  The  lettuce  was  most  attractive  in  appearance. 
It  appealed  to  consumers  who  wanted  several  heads,  and 
by  watering  the  balls  of  earth  they  could  keep  the  heads 
crisp  and  tender  until  the  last  leaf  was  consumed.  This 
plan  of  marketing  also  enables  the  grocer  to  keep  the 
plants  for  several  days,  if  necessary,  in  a  perfectly  fresh 
condition.  While  there  are  some  arguments  in  favor  of 
pot  culture,  it  has  not  appealed  to  commercial  growers. 
This  method  necessarily  involves  more  labor  in  growing 


224 


VEGETABLE   FORCING 


Fig.  77. — Pot  grown  plant  ready  for  market. 

the  crop  as  well  as  in  marketing  it,  and  can  be  used  only 
for  local  markets. 

Insect  enemies. — The  green  fly  is  recognized  as  the 
most  serious  insect  enemy  of  lettuce.  It  is  controlled 
almost  exclusively  by  fumigating  with  tobacco  or  nico- 
tine preparations,  instructions  for  the  use  of  which  are 
given  on  page  105.  Fumigations  should  be  made  at  regu- 
lar intervals  so  there  will  be  no  possibility  of  the  insects 
becoming  sufficiently  numerous  to  damage  the  crop  or  to 
impair  its  selling  quality. 

The  nematode  sometimes  attacks  the  roots  of  green- 
house lettuce,  though  it  is  not  regarded  as  a  serious 
enemy  of  this  crop. 

White  grubs  may  be  troublesome  in  soils  which  have 
not  been  steam  sterilized.  This  is  the  larval  stage  of  the 
June  bug  or  May  beetle.  Old  compost  heaps  and  manure 
piles  are  favorite  breeding  places.  The  eggs  or  young 
larvae  may  be  introduced  into  the  houses  by  infested  soil 
and  manure,  and  the  grubs  may  cause  considerable  injury 


LETTUCE  225 

to  the  roots  of  fall  lettuce.  If  the  beds  are  sterilized  with 
steam  after  manure  has  been  applied,  there  should  be  no 
trouble  from  this  enemy. 

The  white  fly  is  found  sometimes  on  lettuce,  but 
seldom  in  numbers  large  enough  to  cause  any  consider- 
able damage  to  the  crop. 

The  green  cabbage  worm  is  sometimes  a  pest  of  the 
fall  lettuce  crop.  When  it  appears  in  numbers  large 
enough  to  cause  concern,  fresh  pyrethrum,  one  part 
mixed  with  six  parts  of  flour  and  dusted  on  the  plants 
when  they  are  moist,  will  be  found  effective  in  killing  the 
larvae.  Pyrethrum  when  exposed  to  the  air  soon  loses  its 
poisonous  principle  and  thus  becomes  harmless  to  human 
life. 

Snails  feed  on  lettuce  and  they  may  appear  in  soils 
which  have  not  been  steam  sterilized.  Air-slaked  lime, 
dusted  on  the  soil  and  plants,  is  recommended  to  check 
the  ravages  of  snails. 

Cutworms  may  also  feed  on  lettuce  growing  in  soil 
which  has  not  been  sterilized  with  steam.  They  feed  at 
night  and  may  be  killed  by  placing  paris  green  or  other 
poison  on  lettuce  leaves  which  are  scattered  over  the 
ground  where  the  crop  has  been  cut  and  left  for  a  few 
nights.  In  beds  in  which  the  plants  are  not  ready  to 
harvest,  poisoned  bran  mash  will  prove  effective.  Paris 
green  is  mixed  with  dry  bran  until  the  latter  is  slightly 
tinted.  A  sweet  solution  is  made  by  mixing  one  quart  of 
molasses  with  ten  quarts  of  water,  and  then  mixed  with 
enough  of  the  poisoned  bran  to  make  a  mash.  A  table- 
spoonful  of  the  mash,  which  the  cutworms  prefer  to 
lettuce,  is  placed  at  frequent  intervals  on  the  beds. 

Diseases. — There  are  several  diseases  of  greenhouse 
lettuce,  but  the  most  serious  is  known  as  the  drop 
(Sclerotinia  libertiana  Fckl.).  It  is  most  likely  to  appear 
during  cloudy  weather  when  the  temperature  of  the 
house  is  too  highland  insufficient  attention  is  given  to 


226  VEGETABLE   FORCING 

ventilation.  The  fungus  first  causes  the  wilting  of  the 
outside  leaves  of  the  plant,  and  finally  the  rotting  of  the 
stem  at  the  surface  of  the  ground.  Head  lettuce  is  most 
susceptible  to  attack,  but  the  disease  often  appears  on 
Grand  Rapids  and  other  loose-heading  sorts,  and  may 
cause  heavy  losses  in  houses  which  are  not  properly 
sterilized.  This  fungus  is  both  parasitic  and  saprophytic, 
living  over  by  means  of  vegetative  bodies  called 
sclerotinia.  Since  this  fungus  may  live  over  in  the  soil 
or  in  the  old  plant  remains,  it  is  necessary  to  apply  some 
treatment  which  will  kill  the  fungus.  Formaldehyde  or 
steam  sterilization  is  usually  effective.  Thorough  ven- 
tilation, careful  watering  and  the  maintenance  of  proper 
temperatures  are  also  important  factors  in  the  control  of 
this  disease.  There  are  other  forms  of  rots,  but  this  is 
the  most  important. 

Lettuce  mildew  (Brcmia  Lactuccc  Reg.)  appears  some- 
times in  houses  where  there  is  excessive  moisture,  and 
when  there  is  little  sunshine,  but  more  particularly  on 
frame  lettuce  in  the  fall.  It  is  first  seen  on  the  upper 
surfaces  of  the  outer  leaves,  as  yellow  spots,  making  the 
leaves  paler  in  color  and  finally  causing  them  to  wilt.  If 
proper  sanitary  conditions  are  maintained,  mildew  is  not 
likely  to  cause  serious  losses. 

Gray  mold  (Botrytis  vulgaris)  often  accompanies  let- 
tuce drop.  It  is  entirely  saprophytic  and  does  not  spread 
so  rapidly  as  lettuce  drop.  The  edges  of  the  leaves  wilt 
and  the  leaves  soon  droop  and  die,  their  surfaces  becom- 
ing covered  with  gray  mycelium.  Thorough  sterilization 
with  steam  or  formalin  is  effective  as  a  preventive 
measure. 

Dwarf,  stunted  heads  or  tufts  of  leaves,  generally 
called  rosettes,  sometimes  appear  in  beds  of  lettuce. 
They  are  most  commonly  caused  by  the  fungus  Rhizoc- 
tonia,  which  feeds  on  the  roots  of  lettuce  plants  and  thus 
interferes  with  their  proper  nutrition.  As  the  old  roots 


LETTUCE  227 

die,  new  ones  form,  but  the  plants  do  not  thrive. 
Doubled  or_ twisted  roots  (Fig.  74),  due  to  careless  trans- 
planting, may  result  in  dwarfed  plants.  Excessive 
applications  of  fertilizers,  or  unfavorable  soil  conditions, 
may  cause  the  formation  of  rosettes.  Gray  mold  or  other 
diseases  which  attack  and  cause  the  loss  of  the  outer 
leaves  may  have  the  same  effect  in  causing  the  develop- 
ment of  tufts  of  short  leaves  instead  of  fully  developed 
heads.  When  a  fungus  is  the  direct  cause  of  this  ab- 
normal growth,  sterilization  with  steam  or  formaldehyde 
is  effective  as  a  preventive  measure. 

The  excessive  drying  out  of  the  soil  frequently  pro- 
duces a  "rosette"  appearance  of  the  plants. 

Sometimes  the  margins  of  the  leaves  wilt  and  die,  thus 
injuring  the  selling  quality  of  the  plants.  This  is  a  dis- 
ease, the  result  of  a  physiological  disturbance  called  "tip 
burn/'  that  may  occur  on  bright,  clear  days  when  the 
temperature  of  the  houses  is  70  degrees  or  above,  follow- 
ing a  season  of  cloudy  weather.  With  good  management 
in  the  regulation  of  soil  and  atmospheric  conditions  in 
the  house,  tip  burn  is  not  likely  to  occur. 

Electro-culture. — Experiments  made  at  several  agri- 
cultural experiment  stations  show  that  electric  light  is 
beneficial  to  the  growth  of  lettuce.  The  most  extensive 
studies  were  made  at  the  stations  of  Cornell  University, 
West  Virginia  and  Massachusetts.  W.  W.  Rawson,  a 
large  commercial  grower  near  Boston,  was  pleased  with 
the  results  for  a  number  of  years,  but  he  finally  abandoned 
the  use  of  electric  lights  for  hastening  the  growth  of  let- 
tuce. While  reports  of  the  stations  are  rather  favorable, 
commercial  growers  have  not  regarded  electro-culture  as 
a  practical  business  proposition. 

Harvesting. — No  general  rule  can  be  given  concerning 
the  proper  time  to  harvest  lettuce,  because  so  many 
factors  enter  into  the  question.  If  the  heads  are  to  be 
sold  by  the  dozen  or  hundred,  they  should  be  cut  just  as 
soon  as  they  are  large  enough  to  satisfy  the  market  re- 


VEGETABLE  FORCING 

quirements.  The  allowance  of  more  time  would  nec- 
essarily lower  profits  for  the  year,  unless  the  crop  were 
held  for  higher  prices.  Some  markets  will  handle  by  the 
dozen,  plants  which  have  been  in  the  permanent  beds 
only  4  to  5  weeks,  and  pay  good  prices  for  them.  Under 
such  conditions  it  would  be  folly  to  defer  cutting  for  even 
a  day. 

The  quality  of  the  heads,  as  discussed  on  a  previous 
page,  should  also  have  consideration.  The  quality  of  head 
and  Romaine  lettuce  is  particularly  influenced  by  the  time 
of  cutting. 

Prices  should  also  be  taken  into  account.  For  example, 
if  lettuce  is  selling  at  5  cents  a  pound  and  there  are  evi- 
dences of  a  stronger  market,  larger  net  earnings  might 
be  realized  by  holding  the  crop  or  at  least  not  cutting  in 
very  large  amounts  for  a  few  days  or  perhaps  a  longer 
period.  Again,  if  the  crop  is  moving  at  a  high  figure,  and 
there  are  special  reasons  why  a  decline  in  price  may  occur, 
the  crop  should  be  moved  more  rapidly,  though  if  many 
large  growers  who  supply  the  same  markets  should  do 
this  at  the  same  time,  prices  would  be  almost  certain  to 
be  forced  down.  Organization  of  and  co-operation  among 
the  growers,  however,  should  result  in  uniform  distribu- 
tion and  help  to  maintain  remunerative  prices. 

The  condition  of  the  plants  which  are  to  take  the  place 
of  the  lot  to  be  marketed  is  also  a  factor.  If  they  are  be- 
coming spindling  and  overgrown,  it  may  be  better  to  sell 
the  marketable  heads  at  a  sacrifice  rather  than  to  sacrifice 
the  quality  of  the  next  lot  of  plants. 

When  the  crop  is  sold  by  weight,  the  size  of  the  plants 
should  have  the  most  careful  consideration.  The  maxi- 
mum weight  of  a  plant,  produced  under  favorable  condi- 
tions, depends  primarily  upon  the  length  of  time  it  is 
allowed  to  grow  in  the  permanent  bed.  If  large  plants 
are  transplanted  from  pots  to  the  permanent  bed,  fairly 
heavy  plants  may  be  produced  in  four  or  five  weeks, 
provided  there  is  considerable  sunshine.  It  is  seldom, 


LETTUCE 


229 


however,  that  lettuce  which  is  to  be  sold  by  weight  is 
cut  in  less  than  six  weeks  from  setting  in  the  beds,  and 
sometimes  it  is  given  12  to  14  weeks  in  order  that  maxi- 
mum weights  may  be  obtained. 

Records  made  at  The  Pennsylvania  State  College  show 
how  rapidly  plants  gain  in  weight  after  they  have  been 
in  the  beds  about  four  weeks.  For  example,  Grand  Rapids 
lettuce,  which  had  been  growing  in  the  beds  for  four 
weeks,  was  cut  February  15,  and  the  plants  averaged 
three  ounces  each.  February  22,  another  lot  of  plants 


Fig.  78. — Grand  Rapids  lettuce. 

of  the  same  age,  were  cut  from  the  same  bed,  and  they 
averaged  4  5-6  ounces  per  plant.  February  29,  a  third 
lot  was  harvested,  and  these  averaged  ll/2  ounces  per 
plant.  There  was  much  sunshine  during  the  two-week 
period  and,  as  the  figures  indicate,  the  growth  was  rapid. 
It  will  be  observed,  too,  that  the  gain  in  weight  was  much 
greater  during  the  second  week.  The  lettuce  was  sold 
at  12  cents  a  pound.  It  was  large  enough  at  four  weeks 
from  planting  to  satisfy  local  markets,  but  a  gain  of  1.7 
cents  a  plant  per  week  was  made  by  holding  it  for  a 
longer  period.  The  plants  were  set  8  by  8  inches  apart 
and  the  weekly  gain  per  100  square  feet  was  $3.83.  On 
an  acreage  basis  the  gain  per  week  would  be  over  $1,500. 
It  will  be  seen  at  once  why  most  of  the  large  growers  who 


230  VEGETABLE  FORCING 

sell  by  weight  are  reluctant  about  harvesting  the  crop 
until  nearly  the  maximum  weight  has  been  attained,  and 
this  requires  a  much  longer  period  in  the  winter  than  dur- 
ing the  fall  or  spring. 

Three  ounces  to  the  head,  of  Grand  Rapids,  is  con- 
sidered light.  Growers  who  ship  in  baskets  and  sell  by 
weight  average  between  four  and  five  ounces  to  the  plant. 

Six  to  eight-ounce  plants  are  considered  medium  to 
heavy,  and  eight  to  ten  or  more,  very  heavy.  A  large 
grower  of  Grand  Rapids,  who  ships  in  barrels,  plants 
9  by  9  inches  apart  and  grows  very  large  heads.  It  is  not 
unusual  for  these  plants  to  be  in  the  beds  from  10  to  12 
weeks. 

Lettuce  is  cut  with  knives  and  conveyed  in  baskets, 
crates  or  barrels  to  the  packing  shed  where  it  is  prepared 
for  market. 

Marketing. — Lettuce  should  be  carefully  trimmed  of 
all  defective  outside  leaves.  Some,  growers  do  this  at 
the  beds,  as  the  crop  is  cut,  while  others  prefer  to  trim 
the  plants  in  the  packing  room.  The  heads  should  then 
be  washed  to  remove  any  soil  or  plant  lice  that  may  be 
on  them.  The  most  thorough  cleanliness  is  obtained  by 
holding  the  heads  under  a  spigot  of  pure  running  water. 
Some  growers  dip  the  heads  in  tanks  of  water.  Wash- 
ing is  also  essential  to  insure  the  lettuce  arriving  at  the 
market  in  a  fresh,  crisp  condition.  That  is,  the  water 
which  remains  on  the  heads  after  they  have  been  washed 
provides  the  necessary  supply  of  moisture  to  prevent 
wilting  for  several  days,  if  the  packages  are  covered. 

Various  packages  are  used  for  the  shipment  of  lettuce. 
Many  of  the  large  commercial  growers  who  ship  to  dis- 
tant points  use  barrels.  Second-hand  sugar  barrels  are 
used  in  large  numbers  for  this  purpose.  They  are 
especially  desirable  for  winter  shipments,  on  account  of 
the  thorough  protection  that  can  be  given  the  lettuce.  In 
cold  weather  the  inside  of  the  barrel  should  be  lined  with 
paper.  In  warm  weather  several  ventilating  holes  should 


LETTUCE  231 

be  cut  in  the  barrel.  Three  or  four  holes  are  bored  in  the 
bottom  of  the  barrel  for  drainage  if  the  packed  barrel  is 
first  immersed  in  water.  A  plan  followed  in  a  10-acre 
Ohio  range  is  to  take  the  barrels  on  a  cart  (Fig.  55)  to 
the  beds,  where  the  lettuce  is  cut,  trimmed  and  packed 


Fig.  79. — A  basket  of  lettuce  ready  for  market. 

with  the  stems  of  the  plants  in  the  center  of  the  barrel. 
The  heads  are  pressed  down  gently  as  the  packing  pro- 
ceeds, until  the  barrels  are  slightly  more  than  full.  They 
are  then  conveyed  on  the  two-barrel  cart  to  the  packing 
house,  weighed,  and  burlap  covers  placed  over  the  lettuce, 
with  paper  underneath  if  additional  protection  is  nec- 
essary for  shipment  during  cold  weather.  The  top  hoop 
of  the  barrel  is  removed  before  the  lettuce  is  packed,  after 
which  it  is  forced  down  over  the  burlap  and  secured  with 
a  few  small  nails.  The  packed  barrel  is  forced  under 
water  with  a  special  device  and  held  there  for  about  three 
minutes,  when  it  is  removed  and  allowed  to  drain. 

A  large  percentage  of  the  Grand  Rapids  variety  is 
marketed  in  splint  baskets  (Fig.  79)  of  14  quarts  capacity. 
These  may  be  bought  in  1,000  lots  at  3  cents  or  less  apiece. 
From  three  to  six  pounds  of  lettuce  can  be  packed  in  a 


232 


VEGETABLE  FORCING 


basket,  but  some  of  the  markets  prefer  only  three  pounds 
in  each  basket.  The  basket,  after  being  filled,  is  wrapped 
with  brown  paper  which  protects  the  lettuce  from  cold 
weather  and  keeps  it  clean.  This  is  considered  a  very 
satisfactory  package. 

Many  growers  in  New  York  and  throughout  the  New 
England  States  use  bushel  boxes  for  local  markets,  and 
they  are  popular  packages  with  both  producers  and 
dealers.  Larger  boxes  are  used  sometimes  for  distant 
shipments.  Figure  80  shows  trays  of  fancy  head  lettuce 
sold  in  the  London  market. 


Fig.  80. — Choice   head  lettuce   grown  in   England. 

Various  forms  of  crates  are  also  used,  especially  for 
shipping  head  lettuce. 

Yields  and  returns. — The  yield  from  a  given  area  that 
is  well  managed  will  depend  mainly  on  the  time  of  har- 
vesting each  crop.  A  successful  grower  of  Grand  Rapids 
considers  4,500  pounds  a  good  yield  for  a  fall  crop  from 
a  30  by  200-foot  house;  3,000  for  winter  and  5,000  to 
6,000  for  spring.  One  pound  per  square  foot  is  a  good 
yield. 

The  price  of  lettuce  when  sold  by  the  dozen  heads 
varies  from  20  cents  to  75  cents,  and  occasionally  more 


LETTUCE  233 

than  75  cents  for  large  heads  of  high  quality.  Romaine 
lettuce  may  sell  for  $1  or  more  a  dozen  heads.  The  price 
a  pound  for  Grand  Rapids  ranges  from  4  cents  to  20  cents. 
It  is  very  doubtful  whether  any  profit  is  made  even  in  the 
best-managed  houses  when  the  price  is  5  cents  or  less  a 
pound,  and  most  growers  probably  lose  money  at  6 
cents.  Ordinarily,  the  price  ranges  from  7  to  12  cents  a 
pound.  Prices  average  higher  from  January  1  to  April  1 
than  at  any  other  time. 

Growers  estimate  that  it  costs  from  2  to  3  cents  a  head 
to  produce  head  lettuce  in  the  late  fall  and  winter  and 
15  to  20  per  cent  less  in  the  spring. 


CHAPTER  XV 
CAULIFLOWER 

History. — Cauliflower  has  been  grown  in  this  country 
since  the  earliest  days  of  vegetable  forcing.  At  first  its 
culture  as  a  forcing  crop  was  limited  to  frames.  Sash 
were  then  used  to  construct  low,  cheap  houses  which  were 
generally  heated  by  means  of  flues.  With  the  develop- 
ment of  the  greenhouse  industry  an  occasional  gardener, 
especially  on  Long  Island,  tried  cauliflower.  Today, 
cauliflower  is  grown  under  glass,  to  at  least  some  extent, 
near  most  of  the  large  centers  of  population. 

Importance. — Cauliflower  is  not  generally  regarded  as 
a  very  important  forcing  crop.  It  is  shipped  during  the 
forcing  season  in  large  amounts  from  California  and  the 
South,  so  that  prices  now  are  not  nearly  so  encouraging 
as  they  were  years  ago.  The  quality,  however,  is  superior 
to  that  of  cauliflower  which  is  grown  in  the  open  ground, 
so  that  there  will  always  be  at  least  a  fair  demand  for  the 
greenhouse  product.  It  is  probable  that  cauliflower  could 
often  be  profitably  substituted  for  lettuce,  and  it  would 
thus  relieve  or  prevent  market  congestion.  While  it  is 
now  grown  in  small  lots  in  hundreds  of  frames  and  green- 
houses, and  in  large  areas  in  a  few  houses,  there  is  a  feel- 
ing among  greenhouse  men  that  the  crop  ought  to  occupy 
a  more  important  place  in  the  forcing  industry.  The  un- 
certainty of  getting  good  seed  has  undoubtedly  been  a 
deterrent  to  many.  We  have  reason  to  believe  that  the 
seed  problem  has  been  solved  (see  page  235),  and  that 
the  industry  will  develop  during  the  next  few  years.  By 
using  dependable  seed  and  proper  methods  of  inter- 
cropping, the  forcing  of  cauliflower  in  greenhouses  that 
are  properly  managed  should  pay  satisfactory  profits. 

Beds  vs.  benches. — Experiments   made  by  Bailey  at 

234 


CAULIFLOWER 


235 


Fig.  81. — Cauliflower.     Almost  every  plant  produced  a  head. 

Cornell  University  showed  that  ground  beds  (Fig.  81) 
were  much  superior  to  raised  benches  with  bottom  heat 
for  the  forcing  of  cauliflower.  A  smaller  percentage  of 
the  plants  on  the  benches  produced  marketable  heads, 
which  were  also  smaller  and  poorer  in  quality.  It  is  more 
difficult,  in  the  raised  beds,  to  maintain  proper  soil  mois- 
ture conditions,  which  is  one  of  the  most  important 
factors  in  growing  cauliflower.  With  proper  care  the 
crop  can  be  grown  successfully  on  raised  beds,  but  it  is 
a  much  more  certain  proposition  in  ground  beds,  to  say 
nothing  of  the  expense  of  constructing  and  repairing 
benches. 

Varieties. — Only  two  varieties,  Erfurt  and  Snowball, 
(Fig.  82)  are  used  to  any  considerable  extent  for  forcing. 
They  are  early  and  compact  growers,  and  they  produce 
beautiful  heads  of  the  highest  quality.  The  character  of 
the  strain  selected  is  of  much  greater  importance  than  the 
variety,  for  the  best  strains  of  either  variety  are  excellent 
for  growing  under  glass. 

Seed. — Experienced  growers  fully  realize  the  necessity 
of  using  good  seed.  They  have  learned  that  the  use  of 


236 


VEGETABLE  FORCING 


poor  seed  may  result  in  almost  a  total  failure,  because 
many  of  the  plants  may  not  produce  heads  at  all,  and 
those  that  do  form  are  small  and  undesirable.  Most  of 
the  cauliflower  seed  used  in  the  United  States  is  grown 
in  Denmark  and  France.  Much  of  this  seed  does  very 
well  under  glass,  but  there  is  nearly  always  some  concern 
as  to  whether  the  results  will  be  wholly  satisfactory.  On 
account  of  the  uncertainty  of  the  crop  when  forced  from 
imported  seed,  Shoemaker  of  the  United  States  Depart- 


Fig.  82. — A  typical  head  of  greenhouse  grown  cauliflower. 

ment  of  Agriculture  has  been  conducting  experiments  in 
growing  seed  in  greenhouses.  Small  packets  of  the  Gov- 
ernment seed  have  been  supplied  to  various  agricultural 
experiment  stations  as  well  as  to  practical  growers,  and 
the  crops  produced  from  this  seed  have  been  highly  satis- 
factory. He  believes  that  cauliflower  seed  which  is  to 
be  used  for  forcing  purposes  should  be  grown  under 
glass,  and  we  are  indebted  to  him  for  the  following  in- 
formation relating  to  the  subject: 

"In  brief,  our  method  of  culture  in  the  greenhouse  has  been  about 
as  follows :    We  have  found  that  we  can  make  two  crops  of  com- 


CAULIFLOWER  237 

mercial  cauliflower  in  our  greenhouses  at  Arlington  Farm.  If  you 
have  seen  these  houses  you  will  remember  they  are  not  supplied  with 
side  ventilation  and  so  are  more  or  less  unsuitable  for  crops  which 
run  into  hot  weather  in  the  spring,  since  it  is  very  difficult  to  keep 
temperatures  down  to  the  proper  degree.  Our  most  uniform  success 
with  a  crop  oi  seed  has  come  with  the  first  planting,  seed  of  which 
is  usually  sown  about  the  middle  of  September.  This  crop  is  in 
marketable  condition  about  Christmas,  and  if  allowed  to  stay  in  the 
benches  immediately  shoots  to  seed  and  the  seeds  are  ripe  for  har- 
vest in  late  April  or  early  May.  Our  second  crop  of  cauliflower 
goes  into  the  house  as  soon  as  the  first  one  is  out.  Seed  of  this 
crop  is  planted  the  end  of  October  or  November  1  and  is  trans- 
planted into  the  house  about  January  10.  If  the  spring  does  not 
prove  to  be  too  hot  this  will  set  a  very  good  crop  of  seed  and  will 
be  ready  for  harvesting  the  latter  end  of  May  or  June  1.  Our 
plants  are  set  in  the  greenhouse  for  seeding  about  18  inches  apart 
each  way.  I  am  inclined  to  think  that  the  chances  of  success  would 
be  considerably  increased  by  having  solid  beds  rather  than  raised 
benches.  We  find  that  our  troubles  from  disease  invariably  begin 
after  the  plant  has  passed  the  marketable  stage,  since  it  undoubtedly 
begins  to  lose  its  resistance  to  disease  which  has  kept  it  going  up 
to  that  time.  I  think  that  it  would  be  quite  necessary  in  going  into 
this  business  to  see  that  the  soil  is  thoroughly  sterilized.  The  best 
crop  that  we  ever  produced  was  from  a  second  planting,  which  gave 
us  19  pounds  of  seed  from  a  greenhouse  50  feet  long  and  20  feet 
wide.  This  is,  I  think,  very  much  better  than  one  could  count  on 
for  an  average." 

Soil. — Most  of  the  soils  in  which  cauliflower  is  forced 
contain  considerable  sand.  It  is  doubtful,  however, 
whether  sand  is  essential  to  the  success  of  the  crop,  es- 
pecially if  manure  is  used  in  ample  amounts.  Neverthe- 
less, as  stated  in  previous  chapters,  some  sand  in  green- 
house soils,  regardless  of  the  vegetables  grown,  possesses 
distinct  advantages.  But  excellent  crops  are  often  forced 
in  heavy  soils. 

Fertilizing. — There  seems  to  be  a  consensus  of  opinion 
that  the  question  of  soil  fertility  is  of  much  greater  im- 
portance than  that  of  soil  texture.  Whatever  may  be  the 
natural  character  of  the  soil,  it  must  be  heavily  fertilized 
in  order  to  grow  cauliflower  successfully.  There  must 


238  VEGETABLE  FORCING 

be  no  lack  of  organic  matter,  for  this  is  important  from 
the  standpoint  of  plant  food  as  well  as  from  that  of  the 
most  favorable  physical  conditions  of  the  soil.  A  con- 
stant and  uniform  supply  of  moisture  in  the  beds  is  of 
the  utmost  importance,  and  an  abundance  of  decaying 
vegetable  matter  is  essential  for  the  retention  of  moisture. 

There  is  likewise  no  difference  of  opinion  in  regard  to 
the  condition  of  the  manure  when  it  is  applied.  All  agree 
that  it  should  be  well  decayed.  The  pioneer  gardeners 
preferred  cow  manure  for  this  crop,  but  any  kind  of  old 
manure  will  give  satisfactory  results.  Some  of  the  most 
successful  gardeners  in  this  country  and  in  England  rely 
wholly  on  the  use  of  horse  manure.  Top-dressing  with 
poultry  manure  or  liquid  cow  manure  when  the  heads  are 
forming  is  recommended.  Nitrate  of  soda  may  also  be 
used  effectively  as  a  top-dressing.  In  England  a  favorite 
practice  is  to  top-dress  the  beds  with  partly  decayed 
stable  manure. 

A  chemical  analysis  of  cauliflower  was  made  at  the 
Geneva  (N.  Y.)  station,  with  the  following  results: 

Nitrogen        Phosphoric  Potash 

acid 

Head .279  .081  .326 

Leaves    .363  .084  .470 

It  will  be  observed  that  both  the  head  and  the  leaves 
require  large  amounts  of  nitrogen  and  potash.  Inasmuch 
as  most  soils  are  deficient  in  phosphorus,  that  element 
should  also  be  supplied  in  ample  amount. 

Some  of  the  most  successful  commercial  growers 
supplement  stable  manure  with  commercial  fertilizers. 
For  example,  one  of  the  most  extensive  gardeners  on 
Long  Island  uses  for  cauliflower  under  glass  a  fertilizer 
containing  7  per  cent  nitrogen,  8  per  cent  phosphoric 
acid  and  10  per  cent  potash.  It  is  used  at  the  rate  of 
1,000  pounds  to  the  acre.  If  radishes  and  lettuce  are 
grown  between  the  cauliflower  plants,  1,500  pounds  of 
fertilizer  to  the  acre  is  applied. 


CAULIFLOWER  239 

Wood  ashes  are  employed  by  some  growers.  Bone 
meal  at  the  rate  of  one  pound  to  20  square  feet  of  space 
is  beneficial.  Lime  should  be  used  in  the  beds  at  least 
every  other  year. 

Soil  preparation. — Some  of  the  most  careful  growers 
prefer  to  compost  the  soil  and  manure  at  least  half  a  year 
in  advance  of  planting  the  beds.  This  insures  a  thorough 
mixture  of  the  manure  with  the  soil,  and  no  method  will 
give  better  results.  It  is  more  expensive,  however,  than 
preparing  the  beds  in  the  frames  or  greenhouses  by 
applying  stable  manure  and  other  materials  and  incor- 
porating them  thoroughly  with  the  soil.  The  thorough 
methods  used  in  preparing  soils  for  lettuce  will  apply 
equally  well  in  the  preparation  of  beds  for  cauliflower, 
except  that  more  stable  manure  might  be  used.  The 
beds  should  be  at  least  8  inches  deep. 

Starting  the  plants. — Strong,  vigorous  plants  are  essen- 
tial to  a  good  crop.  Many  failures  are  attributable  to 
poor  plants.  They  are  easily  checked  in  growth  and 
when  stunted  they  seldom  recover  sufficiently  to  produce 
good  heads.  It  is  not  uncommon  for  writers  to  say  that 
cauliflower  plants  should  be  started  in  the  same  way  as 
cabbage,  but  the  fact  is  they  demand  much  more  careful 
attention.  The  plants,  too,  are  very  susceptible  to  damp- 
ing-off  fungi.  To  avoid  losses  from  this  source,  the  soil 
should  be  steam  sterilized  and  the  most  careful  attention 
given  to  watering  and  ventilating. 

Sowings  for  the  first  crop  are  generally  made  between 
September  1  and  November  1 ;  if  a  succession  is  desired, 
sowings  should  be  made  at  intervals  of  about  two  weeks. 

It  is  an  advantage  to  sow  in  rows  3  inches  apart,  and 
then  water  may  be  applied  between  the  rows  without 
wetting  the  plants,  which  is  helpful  in  preventing  damp- 
ing-off.  The  seed  should  be  sown  thinner,  too,  than  for 
cabbage,  so  that  the  plants  will  be  strong  and  there  will 
be  free  circulation  of  air  among  them — another  pre- 
ventive measure  of  damping-off. 


240  VEGETABLE  FORCING 

It  is  best  to  make  the  first  transplanting  within  two 
weeks  from  the  date  of  sowing.  The  plants  need  not  be 
more  than  J/£  to  y^  inch  high.  They  should  be  trans- 
ferred from  flats  to  3*/2  or  4-inch  pots  (Fig.  83),  and  it  is 
well  to  plunge  the  pots  in  soil  or  ashes  to  guard  against 
drying  out.  The  plants  should  be  transferred  to  per- 
manent beds  just  as  soon  as  the  pots  are  well  filled  with 
roots. 

A  large  grower  on  Long  Island  made  a  sowing 
November  2.  The  plants  were  set  in  permanent  beds 
January  1  and  he  began  marketing  the  crop  March  15. 


Fig.  83. 
Vigorous  cauliflower  plants   are   essential  to  success. 

Another  Long  Island  grower  sowed  December  1,  and 
transferred  potted  plants  to  permanent  beds  February  1. 
Bailey  made  a  sowing  at  Cornell  University  August  22, 
and  the  first  heads  were  cut  January  13.  Another 


CAULIFLOWER  241 

sowing  made  October  21  produced  marketable  heads 
March  29. 

Seed  that  is  two  years  old  produces  good  results. 
Three  and  four-year-old  seed  must  be  sown  thicker  to  get 
a  satisfactory  stand  of  plants. 

Planting. — The  distance  between  plants  in  the  beds 
varies  from  15  by  15  to  22  by  24  inches  apart.  Moder- 
ately close  planting  seems  to  be  favorable  to  maximum 
returns.  With  a  compact  growing  strain,  15  by  15  or 
14  by  16  will  permit  the  development  of  good  heads. 
Liberal  spacing  is  favorable,  of  course,  to  the  growing  of 
large  heads,  and  if  fancy  prices  can  be  obtained  for  very 
large  heads,  it  may  be  most  profitable  to  grow  them.  A 
common  distance  for  planting  is  16  by  20  inches.  The 
spacing  of  the  plants  may  be  at  such  distances  as  will  be 
most  suitable  for  companion  crops,  such  as  lettuce  and 
radish,  as  discussed  in  the  next  paragraph. 

Intercropping. — A  common  practice  is  to  grow  lettuce 
or  radishes,  or  both  of  these  crops,  between  the  cauli- 
flower plants.  Sometimes  radish  seed  is  sown  broadcast 
in  the  beds  after  the  cauliflower  Las  been  transplanted, 
but  it  is  better  to  sow  the  seed  in  rows.  See  page  254  for 
particulars. 

Watering. — The  beds  should  be  thoroughly  watered 
immediately  after  the  plants  have  been  set.  Thereafter 
water  should  be  added  as  necessary  to  keep  the  soil  moist 
to  the  full  depth  of  the  beds.  This  is  unquestionably 
one  of  the  most  important  factors  in  the  forcing  of  cauli- 
flower. Unusual  care  must  be  exercised  for  at  least  a 
month  after  the  final  transplanting  in  the  beds.  Lack  of 
moisture  at  the  roots  is  certain  to  check  the  growth  of 
the  plants  and  to  result  either  in  no  heads  or  small,  in- 
ferior ones.  At  the  same  time  it  is  equally  important  to 
avoid  over- watering,-  for  this  may  cause  excessive  leaf 
growth  at  the  sacrifice  of  head  formation.  After  the 
plants  begin  to  form  heads,  water  should  be  applied  more 


242  VEGETABLE   FORCING 

copiously  with  a  hose,  care  being  taken  not  to  wet  the 
heads  or  the  foliage,  and  special  fertilization  may  also  be 
given  at  this  period.  Previous  to  the  formation  of  heads 
there  is  no  objection  to  applying  water  as  a  spray. 

A  moist  atmosphere  at  all  times  is  favorable  to.  the 
growth  of  cauliflower.  In  warm,  sunny  weather  it  is  of 
advantage  to  sprinkle  the  walks  with  water  in  order  to 
increase  the  humidity  in  the  house. 

Temperature. — While  cauliflower  is  often  grown  under 
glass  with  lettuce  and  radishes,  it  thrives  best  at  some- 
what higher  temperatures  than  are  required  for  these 
crops.  The  temperature  at  night  may  be  50  to  55  degrees, 
and  by  day  65  to  70  degrees,  though  good  crops  are  often 
grown  with  less  heat. 

Ventilation. — Ventilation  is  essential  to  the  growth  of 
healthy  plants  and  to  the  formation  of  good  heads,  but 
cauliflower  is  very  sensitive  to  cold  drafts,  which  may 
cause  the  leaves  to  droop  and  prevent  head  formation. 
Some  fresh  air  should  be  admitted  to  the  houses  daily, 
but  cold  drafts  should  never  strike  the  plants. 

Cultivating. — The  beds  of  cauliflower  should  be  cul- 
tivated at  frequent  intervals.  This  is  of  special  value  in 
conserving  soil  moisture  and  in  encouraging  the  most 
satisfactory  growth.  One  of  the  chief  objections  to  inter- 
crops of  lettuce  or  radishes  is  that  they  interfere  to  some 
extent  with  thorough  cultivation. 

Insect  enemies. — The  green  aphis  is  the  most  serious 
pest  of  cauliflower  grown  under  glass,  but  it  is  easily 
controlled  by  tobacco  fumigation.  (See  page  105.)  The 
larvae  of  the  cabbage  butterfly  sometimes  feed  on  plants 
started  during  the  fall  months.  Arsenate  of  lead,  or,  if 
preferred,  fresh  pyrethrum  or  insect  powder,  may  be  used 
to  poison  this  pest. 

Diseases. — Cauliflower  is  subject  to  the  same  diseases 
as  cabbage  and  other  brassicae.  The  commonest  are 
soft  rot  or  stem  rot,  black  rot  and  club  root.  They  sel- 


CAULIFLOWER  243 

dom  appear  on  cauliflower  grown  in  greenhouses,  but 
steam  sterilization  of  the  soil  is  a  safe  precaution. 

Frame  culture. — Cauliflower  is  a  popular  frame  crop  in 
some  sections.  It  may  be  intercropped  with  lettuce  and 
radishes.  See  page  399  for  further  data  on  the  culture  of 
this  crop  in  coldframes. 

Head  protection. — Unless  the  heads  or  curds  of  cauli- 
flower are  protected,  they  will  not  be  pure  white  in  color 
when  ready  for  market.  Uncovered  or  unprotected 
heads  are  yellowish  in  appearance  and  cannot  be  sold  at 
as  high  prices  as  pure  white  heads.  Again,  snowy  white 
heads  are  said  to  be  more  tender  in  texture  and  finer  in 
quality. 

Various  methods  are  used  to  protect  the  heads  when 
the  crop  is  grown  out  of  doors.  Among  them  may  be 
mentioned  tying  the  leaves  together  over  the  heads  with 
strings  or  small  bands  of  rye  straw ;  folding  or  breaking 
the  leaves  over  the  heads  and  securing  them  with  tooth- 
picks, or  "tucking"  them  in  an  ingenious  way  so  that 
they  will  remain  in  place.  Although  any  of  the  plans 
used  in  field  culture  may  be  employed  under  glass, 
several  thicknesses  of  brown  paper  placed  over  the  heads 
will  be  found  more  satisfactory.  This  matter  should 
have  attention  when  the  heads  are  about  2  inches  in 
diameter.  It  is  a  simple  matter  to  lift  the  paper  to  deter- 
mine when  the  heads  are  ready  for  market. 

Marketing. — Cauliflower  should  be  harvested  before 
the  hea^s  begin  to  break  or  become  warty.  Early  mar- 
keting ^  essential  from  the  standpoint  of  quality  as  well 
as  appearance.  Heads  which  are  only  3  inches  in  di- 
ameter are  marketable,  but  larger  sizes  command  better 
prices.  Under  the  most  favorable  cultural  conditions, 
most  of  the  heads  should  be  5  to  7  inches  in  diameter, 
especially  if  superior  strains  of  seed  have  been  used. 

The  utmost  care  should  be  exercised  in  cutting  and 
handling  the  crop  .to  protect  the  heads,  which  are  ex^ 


244  VEGETABLE  FORCING 

tremely  tender,  from  bruises  or  other  injuries.  Even  the 
slightest  marks  or  blemishes  will  detract  from  their 
appearance  and  probably  require  the  grower  to  accept  a 
lower  price. 

The  leaves  encircling  each  head  are  trimmed  as  shown 
in  Fig.  84.  Some  markets  prefer  a  "long  trim,"  sortie  a 
"medium  trim"  and  others  a  "short  trim."  The  leaves 


Fig.  84. — Cauliflower  trimmed  for  market.    Head  on  right  trimmed  very  short. 

may  be  removed  very  quickly  with  a  large,  sharp  knife. 
Crates  of  various  dimensions  are  used  for  marketing 
cauliflower  which  has  been  grown  under  glass.  Most  of 
the  crates  are  made  to  hold  either  a  dozen  or  two  dozen 
heads.  Louisiana  gardeners,  who  ship  cauliflower  from 
field  plantations  during  the  early  winter,  use  crates  that 
hold  only  half  a  dozen  heads.  Such  a  crate  should  be 
even  more  valuable  for  the  greenhouse  product.  The 
head  pieces  for  the  Louisiana  crate  are  7  incheo  by  14 
inches  by  ^  inch  in  size.  The  lath  are  3  or  3J4  inches 
by  22  inches  by  J4  inch.  Cottonwood  for  these  crates 
is  preferred  to  any  other  lumber.  The  dimensions  of  the 
crate  must  be  determined  by  the  size  of  the  heads  which 
are  ordinarily  grown.  When  rigid  grading  of  the  differ- 
ent sizes  is  practiced,  and  this  is  always  desirable,  it  is  an 
advantage  to  have  crates  of  various  sizes.  It  is  doubtful 


CAULIFLOWER  245 

whether  greenhouse  cauliflower  should  ever  be  packed  in 
larger  lots  than  a  dozen  heads  to  the  package.  The 
crates  should  be  lined  with  paper,  and  if  a  fancy  trade  is 
to  be  supplied,  it  will  be  a  decided  advantage  to  wrap 
each  head  in  oiled  paper  to  keep  it  clean  and  free  from 
dust. 

Cauliflower  which  has  been  properly  grown  and  sold 
at  average  prices  should  yield  a  gross  return  of  not  less 
than  12  to  15  cents  a  square  foot  of  greenhouse  area. 
Prices  for  good  heads  are  seldom  less  than  $2  a  dozen. 
Perhaps  $2.50  a  dozen  is  about  an  average  price  for  this 
vegetable  when  grown  under  glass. 


CHAPTER  XVI 
RADISH 

Importance. — The  radish  is  commonly  forced  near  all 
large  centers  of  population,  though  in  commercial  im- 
portance it  does  not  approach  lettuce,  the  tomato  or  the 
cucumber.  While  there  is  a  large  demand  for  forced 
radishes,  it  is  an  easy  matter  to  overstock  the  markets. 
Most  growers  believe  that  the  radish,  as  a  forcing  crop, 
does  not  pay  as  well  as  lettuce.  On  the  other  hand, 
many  believe  that  the  crop  deserves  more  attention.  It 
is  one  of  our  best  salad  crops  and  possesses  special  merit 
for  garnishing  or  table  decoration.  Quick  returns  are 
obtained  from  it,  and  it  can  sometimes  be  grown  with 
other  crops,  such  as  lettuce,  and  will  thus  add  to  the 
earnings  of  the  house.  The  radish  may  be  grown  in  low, 
cheap  houses,  where  it  is  impossible  to  force  the  tomato 
or  the  cucumber. 

There  are  times  when  lettuce  growers  would  find  it 
profitable  to  devote  some  of  their  greenhouse  space  to 
the  forcing  of  radishes  and  thus  avoid  market  slumps  of 
lettuce.  It  is  not  a  difficult  crop  to  produce  under  glass, 
though  careful  attention  must  be  given  to  its  various 
cultural  requirements. 

Light. — Probably  no  vegetable  forcing  crop  is  more 
sensitive  to  shade  or  the  lack  of  light  than  the  radish. 
It  may  be  grown  successfully  in  old  houses  admitting 
the  minimum  amount  of  light,  but  the  best  results  are 
obtained  in  houses  of  modern  construction.  Any  ob- 
struction to  the  light  and  sunshine  is  certain  to  favor 
the  development  of  tops  rather  than  large  roots.  The 
shading  of  other  classes  of  plants  should  be  avoided  as 
much  as  possible. 

246 


RADISH      .  247 

Beds  vs.  benches.— The  radish  is  forced  both  on  raised 
benches  and  in  ground  beds.  Most  growers  prefer 
ground  beds.  The  winter  crop  may  be  matured  on  raised 
benches  with  bottom  heat  in  from  one  to  two  weeks  less 
time  than  on  ground  beds.  If  there  are  heating  pipes 
under  the  benches,  great  care  must  be  exercised  to  avoid 
forcing  the  crop  too  rapidly,  as  excessive  top  growth  will 
be  encouraged  at  the  sacrifice  of  good  roots.  The  regu- 
lation of  temperatures  and  soil  moisture  will  require  less 
attention  if  ground  beds  are  used.  On  the  other  hand, 
the  space  under  benches,  if  heating  pipes  are  located 
elsewhere,  may  be  profitably  used  in  forcing  rhubarb 
and  asparagus,  and  with  the  saving  of  time  for  each  lot 
of  radishes  it  is  possible  to  grow  an  additional  crop 
before  planting  the  benches  in  the  spring  with  tomatoes 
or  cucumbers. 

Varieties. — The  large  varieties  which  are  commonly 
grown  out  of  doors  are  not  desirable  for  forcing.  Most 
consumers  prefer  the  small,  turnip-shaped  roots,  and 
these  attain  a  marketable  size  in  much  less  time  than  the 
long-rooted  sorts.  The  early  turnip-shaped  varieties 
may  also  be  grown  much  closer  together,  and  this  is  a 
decided  advantage  in  obtaining  maximum  profits.  The 
best  strains  of  forcing  varieties  have  very  small  tops,  so 
that  the  rows  need  not  be  more  than  4  inches  apart  and 
the  roots  may  stand  very  close  together  in  the  rows. 

The  color  of  forced  radishes  is  an  important  factor. 
As  a  rule,  the  markets  prefer  bright  red  rather  than  dark 
red  roots.  Some  markets  can  dispose  of  a  considerable 
quantity  of  white-tipped  sorts.  The  olive-shaped  varie- 
ties are  often  grown  in  frames. 

The  quality  of  the  different  varieties  should  also  be 
considered.  Icicle,  a  well-known  white  variety,  is  of  very 
high  quality,  and  though  the  color  is  unfavorable  for 
winter  sales,  the  demand  for  this  variety  is  increasing. 

Most  commercial  growers  of  large  experience  prefer 


248  VEGETABLE  FORCING 

Scarlet  Globe  or  one  of  its  numerous  strains.  Among  the 
varieties  which  are  most  commonly  grown  under  glass 
may  be  mentioned  Cardinal  Globe,  White-Tipped  Scarlet 
Globe,  Colonial  Forcing,  Carmine  and  Fireball. 

Soil. — The  finest  radishes  are  invariably  grown  in  soils 
containing  a  considerable  quantity  of  sand.  The  roots  in 
such  soils  are  smoother  and  more  uniform  in  shape  than 
when  they  are  grown  in  clay  or  silt  soils,  and  less  labor 
is  required  to  wash  them.  Excellent  roots  may  be  pro- 
duced in  heavy  soils  which  are  well  supplied  with  or- 
ganic matter,  though  sand  should  be  added  to  the  beds  if 
it  is  possible  or  feasible  to  do  so.  Sand  also  decreases  the 
chances  of  heavy  losses  from  the  attack  of  damping-off 
fungi,  and  facilitates  sowing,  thinning  and  cultivating. 

Fertilizing. — Experiments  and  practical  tests  made  with 
commercial  fertilizers  for  radishes  have  not  given  as  good 
results  as  manure  alone.  Wheeler  (Rhode  Island  Bulletin 
128)  reports  that  no  combination  of  commercial  fertilizer 
applied  with  short-cut  straw  (the  latter  mixed  with  the 
soil  in  sufficient  quantity  to  alter  its  physical  properties) 
gave  as  good  results  as  well-decayed  stable  manure  used 
at  the  rate  of  75  tons  to  the  acre.  It  is  necessary  to  have 
an  abundance  of  available  plant  food,  but  suitable  physical 
properties  of  the  soil  are  of  greater  importance  than  the 
mere  question  of  plant  food.  The  radish  does  not  thrive 
in  any  soil  which  is  lacking  in  vegetable  matter.  The  soil 
must  be  loose  and  friable,  and  for  this  reason  manure 
gives  better  results  than  do  commercial  fertilizers.  It  is 
possible  that  fertilizers  can  be  used  to  advantage  under 
certain  conditions,  but  the  radish  does  not  seem  to  re- 
spond well  to  their  application. 

Fresh  stable  manure  should  never  be  applied  immedi- 
ately before  sowing  radishes,  for  it  is  favorable  to  ex- 
cessive top  growth  instead  of  to  satisfactory  root  develop- 
ment. The  manure  should  be  at  least  several  months  old 
and  fine  enough  to  mix  well  with  the  soil.  An  annual 
application  of  40  tons  of  manure  to  the  acre  of  greenhouse 


RADISH  249 

space  should  give  most  excellent  results.  Some  gardeners 
prefer  to  apply  a  light  dressing  of  manure  before  each 
crop  is  started,  though  a  heavy  application  in  the  fall  will 
be  sufficient  to  grow  several  crops.  Inasmuch  as  it  is 
not  feasible  to  sterilize  the  soil  before  starting  each  crop, 
probably  the  better  practice  is  to  apply  all  of  the  manure 
in  the  fall,  unless  the  grower  is  willing  to  take  chances 
in  using  manure  that  has  not  been  sterilized. 

Soil  preparation. — Directions  for  the  preparation  of 
soils  for  vegetable  forcing  are  given  on  page  70.  As  pre- 
viously stated  successful  growers  of  radishes  apply  well- 
decayed  manure  to  the  beds  either  in  the  fall  or  before 
each  crop  is  started.  A  more  expensive  plan  is  to  compost 
sods  and  stable  manure,  but  this  is  not  considered  prac- 
ticable on  a  large  commercial  scale. 

The  turnip-rooted  varieties  may  be  grown  successfully 
in  beds  only  4  inches  deep.  It  is  better,  however,  on  ac- 
count of  more  favorable  moisture  conditions,  to  make  the 
beds  from  6  to  8  inches  deep,  and  a  greater  depth  will  be 
an  advantage  from  this  standpoint.  It  is  probable,  how- 
ever, that  the  usual  application  of  manure  will  give  the 
best  results  when  incorporated  with  the  soil  in  beds  that 
are  not  more  than  8  inches  deep. 

Seed. — Disappointments  in  the  forcing  of  the  radish 
are  often  due  to  the  planting  of  poor  seed.  Sometimes 
the  seed  is  old  and  does  not  germinate  well,  but  the  most 
common  loss  is  from  seed  of  impure  strains.  The  roots 
from  inferior  seed  may  be  small  and  ill-shaped,  or  a  large 
percentage  of  the  plants  may  not  produce  roots  of  market- 
able size.  Sometimes  the  radishes  do  not  have  the  char- 
acteristic shade  or  color,  and  this  may  result  in  a  heavy 
loss  if  a  special  market  is  to  be  supplied.  Poor  seed  may 
also  produce  large  tops  and  small  roots. 

When  ordering  radish  seed  it  is  important  to  specify 
that  the  best  forcing  strains  are  desired.  Most  of  the  seed 
houses  have  strains  of  special  merit  and  these  should  be 
obtained  if  possible. 


250  VEGETABLE  FORCING 

An  excellent  method  is  to  buy  small  lots  of  seed  of  the 
desired  varieties  from  different  dealers  and  test  them  in 
the  greenhouse.  Seed  of  the  best  lot  may  then  be  pur- 
chased in  sufficient  quantity  to  last  a  year.  After  the 
larger  shipment  has  been  received  the  additional  precau- 
tion of  another  test  should  be  made  before  sowing  exten- 
sive areas. 

A  small  percentage  of  growers  who  are  forcing  radishes 
under  glass  grow  their  own  seed.  They  claim  that  the 
results  of  home-selected  seed  are  highly  satisfactory  if 
the  work  of  breeding  has  been  properly  managed. 

Many  of  the  most  successful  and  most  extensive  grow- 
ers remove  the  smaller  seeds  by  screening.  Some 
gardeners  discard  one-third  of  the  seed.  Ordinarily,  this 
will  require  a  mesh  that  is  about  one-twelfth  of  an  inch 
in  diameter. 

There  are  numerous  advantages  in  planting  large  seed. 
Among  them  may  be  mentioned  quicker  germination, 
larger  percentage  of  germination,  larger  individual  roots 
and  larger  total  yield.  Extensive  experiments  with  large 
radish  seed  were  made  by  Cummings  (Rhode  Island  Bul- 
letin 177).  The  results  were  so  striking  that  the  com- 
plete report  is  given  as  follows : 

"The  radish  was  selected  partly  because  its  seed  exhibit  much 
variation  in  size  and  weight,  but  chiefly  because  it  is  one  of  the 
shortest  of  the  short-term  crops.  Sixteen  different  trials  were  made 
during  a  period  of  three  years.  Only  two  varieties  were  used,  but 
the  many  trials  made  have  afforded  fairly  uniform  and  consistent 
results.  Observations  made  on  seeds  of  other  varieties  show  the 
same  divergencies  in  size  of  crop,  and  there  seems  to  be  no  reason 
to  suppose  that  the  varieties  chosen  were  in  any  way  abnormal. 

"Attention  was  first  directed  to  the  general  results  of  seed  selec- 
tion with  reference  to  size.  The  relative  values  of  large  and  small 
seed  are  shown  in  the  tables  presented  below : 


RADISH 


251 


Size      Number 
of  of 

seed       plants 


Large 

Small 


Large 

Small 


53 
56 


Weight         Average  Number  1 

of  roots,        weights,        Number      Weight, 
grams  grams  grams 

EARLY  FRENCH  BREAKFAST 

890  11.4  32  510 

425  7.7  4  50 

EARLY  SCARLET  GLOBE 

765  14.4  23  440 

573  10.2  16  220 


Number  2 
Number    Weight, 
grams 


51 


30 
40 


380 
375 


325 
353 


"The  superiority  of  large  seed  is  shown  in  the  greater  weight  of 
the  edible  portion  of  plants,  approximately  a  50  per  cent  increase; 
and  in  the  greater  proportion  of  No.  1  plants,  both  in  terms  of  num- 
bers and  weight.  Forty  per  cent  of  the  crop  grown  from  large 
seed  was  classified  as  No.  1,  while  only  from  7  to  28  per  cent  of  the 
plants  grown  from  small  seed  were  thus  classified. 

"After  noting  the  relative  productive  capabilities  of  large  and 
small  seed,  it  then  seemed  necessary  to  observe  other  factors  in  com- 
paring the  different-sized  seeds.  The  following  table  displays  data 
as  to  variations  in  weight  of  seeds  and  number  of  plants  produced, 
together  with  the  quality  and  weight  of  plants  at  the  time  of  harvest. 


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EARLY  FRENCH  BREAKFAST 

Large        4,700    54.4    3,466    74     16,560    13.4    2,688    77.5    21,120       778    23,040 
Medium    4,700     43.5     3,270     70    36,960     11.3     2,077     63.5     14,880    1,193     14,400 


Small 


4,700     24.7     2,316     49     21,960      9.5     1,325     57.2     10,560      991       9,600 


"The  large  seed  outweighed  the  small  by  120  per  cent;  its 
viability  was  better  by  50  per  cent;  the  crop  from  the  same  number 
of  seed  grown  was  117  per  cent  larger  in  terms  of  weights,  104 
per  cent  larger  in  terms  of  numbers,  100  per  cent  greater  in  terms 
of  weight  of  edible  roots,  and  the  tops  were  135  per  cent  heavier. 
The  total  edible  weight  of  the  crop  secured  where  small  seed  was 
used  was  just  50  per  cent  of  that  harvested  from  the  sowing  of 
large  seed. 

"The  studies  noted  above  were  followed  by  others  at  germination 
time.  Weights  were  made  of  the  embryos  during  the  first  5  days 


252  VEGETABLE  FORCING 

after  applying  moisture  to  the  seeds.    The  differences  in  weight  arc 
shown  in  the  table  that  follows: 

WEIGHT  OF  EMBRYOS 
Relative  Weights  of  15   Seeds  During  Germination 


Size 
of 
seed 

Weight 
of  seed, 
grams 

First 
day, 
grams 

Second 
day, 
grams 

Third 
day, 
grams 

Fourth 
day, 
grams 

Fifth 
day, 
grams 

Large 
Medium 
Small 

.477 
.432 
.316 

.654 

.484 
.411 

.885 
.560 
.434 

1.109 
~.*4"62 

1.127 
.849 
.581 

1.307 
1.042 
.703 

"The  greater  weight  of  the  embryos  of  the  large  seed  should  be 
associated  with  the  greater  weight  of  mature  plants,  as  noted  in  a 
preceding  table.  It  seemed  also  desirable  to  correlate  the  matter  of 
greater  weight  with  that  of  the  relative  sizes  of  embryos;  con- 
sequently there  is  added  another  table  showing  their  measurements. 

SIZE  OF  EMBRYOS 

Days    Number                  Large  Medium  Small 

after           of        Width  of    Length  of  Width  of    Length  of  Width  of    Length  of 

germi-    measure-  leaves,       embryo,  leaves,        embryo,  leaves,        embryo, 

nation  ments           mm.             mm.  mm.               mm.  mm.               mm. 

1  15  7.3  25  6.9  24  5.6  21 

2  15  7.4  33  6.6  .27  5.5  21 

3  15  7.3  41  6.3  32  5.3  22 

4  30  7.4  43  6.8  36  5.5  31 

5  30  7.7  47  7.2  39  5.9  27 

"Beginning  with  the  first  day  after  germination,  and  continuing 
for  five  days,  it  was  found  that  the  embryos  of  large  seeds  have 
wider  and  longer  leaves  than  those  of  small  seeds,  while  the  embryos 
of  medium-sized  seeds  are  of  intermediate  dimensions.  If  plants 
are  larger  from  their  start,  and  even  before  germination,  it  is  to 
be  expected  that  they  will  continue  to  prove  superior  in  size  as  they 
develop. 

"Observations  have  shown  that  radishes  grown  from  large  seed 
attain  the  edible  stage  sooner  than  those  grown  from  small  seed. 
It  was  thought  that  on  this  account  they  might  contain  more  water ; 
hence  a  number  of  plants  were  trimmed  as  for  eating  and  their  dry- 
matter  contents  determined : 


Size 
of 
seed 

Large 
Medium 
Small 

Weight  before 
drying, 
grams 

43.8 
29.2 
31.3 

Weight  after 
drying, 
grams 

1.84 
1.55 
1.59 

Water, 
per  cent 

95.79 
94.70 
94.94 

Dry 
matter, 
per  cent 

4.21 
5.30 
5.06 

RADISH  253 

"This  table  is  representative  of  several  similar  and  concordant 
determinations  made  but  not  published.  It  shows  the  lower  dry- 
matter  content  of  plants  grown  from  large  seed.  The  plants  were 
of  the  same  age  from  seed,  but  were  not  of  the  same  degree  of 
maturity.  Plants  grown  from  small  seed  were  about  a  week  later 
in  coming  to  edible  maturity  than  those  grown  from  large  seed. 
It  is  doubtful  if  an  exact  comparison  could  be  made  by  allowing 
the  small  seed  crop  to  grow  another  week,  for  by  so  doing  changed 
soil  and  air  conditions  might  intervene.  However,  the  water  content 
of  a  radish  is  not  a  matter  to  cavil  about.  It  is  always  extremely 
high.  Radishes  are  not  eaten  for  the  food  they  contain,  but  as  a 
relish.  Good  quality  radishes  must  be  rapidly  grown,  crisp  and 
succulent,  no  matter  how  high  their  water  content.  Aside  from  size 
as  related  to  quality,  the  plants  grown  from  small  seed  were  as  good 
as  those  grown  from  large  seed. 

"The  source  of  seed,  whether  from  one  parent  or  several,  seems 
to  make  little  if  any  difference  in  the  value  of  the  product.  The 
following  tables  show  the  results  of  seed  sorting  according  to  size 
when  the  seeds  in  a  series  are  derived  from  the  same  plants,  the 
purpose  in  this  instance  being  to  eliminate  the  influence  of  indi- 
viduality in  different  plants,  and  to  insure  similarity  in  such  parental 
factors  as  relate  to  vigor  and  general  growth  force. 
RADISH  SEED  OF  DIFFERENT  SIZES  DERIVED  FROM  THE  SAME  PARENT 

«"  I  I  afll  ^ 

C  a  a  b.S  rt     ^  «  « 


g 

•2 

I 

Planted  December  30,  harvested  March  1 

Large                 39            737         18.9  335          8.6  402          10.3      1.7         20 

Medium            40            678          17.0  307          7.7  371            9.3       —         — 

Small                  36            549         15.3  241          6.7  308            8.6       —         — 

Planted  January  6,  harvested  March  1 

Large       39     475    12.2  280    7.2  195     5.0   1.3    35 

Medium     44     502    11.4  292    6.6  210     4.8   —    — 

Small       38     372     9.8  233    6.1  139     3.7   —    — 

Planted  December  30,  harvested  March  1 

Large               100          1,658          16.6  777          7.8  881             8.8      2.3          35 

Medium           107          1,503          14.1  713          6.7  790            7.4       —          — 

Small               103          1,248          12.1  577          5.5  671           6.5       —         — 


Number  of  plam 

Total  weight  of 
grams 

Average  weight 
plants,  grams 

f 
o 

Jc 
bo 

•c 

Average  weight 
tops,  grams 

Weight  of  roots, 

Average  weight 
roots,  grams 

°   (O  -g 

ill 

!£i 
<°* 

Percentage  gai 
large  oyer  smal 
in  weight  of  r 

254  VEGETABLE  FORCING 

"Fully  as  emphatic  results  fol\ow  the  selection  of  seed,  all  of 
which  is  from  the  same  plant,  as  were  secured  by  selection  on  the 
size  basis,  irrespective  of  parentage;  so  that  the  use  of  commercial 
seeds  of  large  size  has  practical  bearing  irrespective  of  considera- 
tions of  parental  vigor. 

"Large  seed,  regardless  of  its  source,  of  mixed  or  unmixed 
heritage,  is  superior  to  small  seed  of  the  same  source,  because  it 
gives  larger  plants,  greater  uniformity  in  stand  at  edible  maturity, 
and  a  maturation  gain  of  from  7  to  10  days.  In  greenhouse  culture 
and  elsewhere,  when  space  is  valuable  or  earliness  imperative,  an 
economic  gain  may  be  expected  from  the  use  of  large  seed.  In 
actual  practice  this  advantage  may  be  secured  by  sifting  out  and 
discarding  the  small  seed." 

Sowing. — The  beds  should  be  smooth,  level  and  fairly 
moist  before  the  seed  is  sown.  An  occasional  grower 
sows  broadcast,  but  drills  possess  many  advantages.  The 
space  between  rows  varies  from  3  to  6  inches.  Close 
planting  has  a  tendency  to  produce  small  roots,  to  retard 
their  maturity,  and  to  encourage  damping-off  fungi  and 
large  tops.  The  rows  may  be  relatively  close  if  low  tem- 
peratures are  to  be  maintained. 

Only  an  occasional  grower  plants  as  close  as  3  inches 
and  very  few  allow  6  inches  between  rows.  The  most 
common  spacing  is  4  inches,  though  many  allow  4^2  to  5 
inches.  Varieties  which  produce  small  tops  and  small 
roots  may  be  planted  at  minimum  distances.  A  success- 
ful grower  of  the  Middle  West  spaces  the  rows  4^2  inches 
apart.  When  the  bulk  of  the  crop  is  pulled,  the  second 
sowings  are  made  midway  between  the  first,  so  that  the 
new  and  the  old  rows  are  only  2^4  inches  apart  for  per- 
haps a  week.  This  plan  of  intersowing  is  the  most  suc- 
cessful when  the  plants  are  thinned  to  from  8  to  10  to 
the  linear  foot  of  row. 

The  time  for  making  each  sowing  must  be  determined 
by  market  conditions,  season  of  the  year,  varieties  grown, 
temperatures  of  the  house  and  whether  benches  or  ground 
beds  are  used.  From  four  to  eight  weeks  are  required 
for  the  button  varieties  to  mature.  The  amount  of  sun- 


RADISH  255 

shine  and  length  of  days  are  important  factors.  In  April 
and  May,  roots  of  small  size  may  be  grown  in  four  weeks, 
while  twice  this  length  of  time  may  be  required  at  mid- 
winter. There  is  no  reason  why  the  first  sowings  should 
not  be  made  in  October  or  perhaps  earlier  in  houses 
which  can  be  thoroughly  ventilated.  Radishes  generally 
sell  at  good  prices  immediately  before  and  during  the 
Christmas  holiday  season.  Scarlet  Globe  sown  about 
November  15  should  produce  marketable  roots  a  few  days 
before  Christmas.  The  beds  should  be  resown  as  rapidly 
as  they  are  cleared. 

Most  growers  make  rows  or  furrows  for  the  seed  by 
means  of  a  thin,  narrow  board,  long  enough  to  extend 
nearly  across  the  bed.  By  drawing  it  back  and  forth  a 
few  times,  a  furrow  is  quickly  made.  It  need  not  be  more 
than  half  an  inch  deep.  The  seed  is  distributed  with  the 
thumb  and  fingers  or  with  an  envelope.  Twenty  seeds 
to  each  linear  foot  of  row  should  give  a  good  stand  of 
plants.  The  furrows  are  closed  in  some  convenient  way, 
and  the  beds  firmed  with  a  block  of  wood  and  then 
watered. 

Thinning. — Two  general  policies  are  followed  with 
reference  to  thinning.  One  is  to  sow  enough  seed  to  in- 
sure a  good  stand  of  plants  without  crowding,  and  then 
to  do  no  thinning  until  they  are  large  enough  for  market, 
when  their  removal  will  leave  more  space  for  the  remain- 
ing plants.  With  this  plan  of  management  more  time  is 
required  for  all  the  plants  on  a  given  area  to  produce 
roots  of  marketable  size.  It  is  claimed  by  some  growers 
that  this  method  is  more  profitable  than  the  usual  plan  of 
thinning  the  small  seedlings. 

The  majority  of  commercial  growers  prefer  to  sow 
plenty  of  seed  and  then  thin  the  plants  soon  after  they 
are  up.  While  this  is  a  somewhat  tedious  task,  there  are 
distinct  advantages  in  thinning.  The  smaller  plants  may 
be  removed,  leaving  only  the  strong,  vigorous  ones  which 
will  be  likely  to  produce  good  roots.  Again,  the  roots 


256  VEGETABLE  FORCING 

will  mature  over  a  much  shorter  period  than  they  will 
when  thinning  is  not  practiced,  and  they  will  be  larger 
and  more  uniform  in  size  and  shape. 

Some  growers  allow  only  ^  to  £4  *ncn  °f  space  be- 
tween plants  of  the  smallest  varieties,  but  this  is  too 
close  for  the  best  development  of  most  varieties.  The 
more  generally  approved  plan  is  to  thin  to  from  8 
to  10  plants  per  each  linear  foot  of  row.  An  inch  and  a 
half  between  plants  is  sufficient  space  for  most  turnip- 
shaped  sorts.  An  occasional  grower  allows  2  inches. 
Larger  roots  are  produced  when  the  spacing  is  liberal, 
and  higher  prices  for  them  may  justify  the  practice. 

Intercropping. — When  radishes  are  used  for  inter- 
cropping with  lettuce  and  cauliflower,  it  is  important  to 
select  varieties  of  light  foliage  and  to  see  that  the  plants 
are  not  crowded.  If  ample  space  is  allowed  between  the 
rows  as  well  as  between  the  plants  in  the  rows,  good 
roots  may  be  grown,  and  there  will  be  no  appreciable 
interference  with  the  lettuce  or  cauliflower. 

Watering. — A  constantly  moist  bed  provides  ideal  con- 
ditions for  the  radish.  Over-watering,  especially  if  tem- 
peratures are  too  high,  is  likely  to  cause  damping-off  of 
the  seedlings.  If  they  escape  this  disease,  they  will  be- 
come top  heavy  and  the  roots  will  be  small  and  late  in 
maturing. 

Beds  should  be  watered  thoroughly  after  the  seed  is 
sown,  and  sufficient  water  should  be  used  at  this  time 
to  require  no  further  applications  until  the  plants  are  up 
and  ready  to  thin.  When  sowings  are  made  under  glass 
in  warm,  bright  weather,  two  or  three  waterings  may  be 
necessary  to  supply  moisture  until  the  plants  are  up. 

The  beds  are  likely  to  dry  out  more  rapidly  next  to 
the  walks,  and  dry  spots  may  appear  here  and  there  which 
will  require  extra  applications  of  water.  Such  places  may 
be  watered  very  quickly  with  a  special  nozzle  attached 
to  a  hose.  Excessive  watering  when  the  radishes  are 


RADISH  257 

nearly  large  enough  to  market  may  cause  the  roots  to 
crack. 

The  radish  thrives  best  in  a  humid  atmosphere.  Over- 
head watering,  which  diffuses  a  mist  over  the  beds,  pro- 
vides the  most  favorable  soil  and  atmospheric  conditions 
so  far  as  moisture  is  concerned. 

Temperature. — Too  high  temperatures  produce  spin- 
dling plants  and  excessive  top  growth,  and  the  roots  will 
be  small.  Too  low  temperatures,  on  the  other  hand, 
cause  slow  growth  and  the  development  of  roots  that  are 
lacking  in  quality.  A  night  temperature  of  43  to  45  de- 
grees and  a  day  temperature  of  55  to  60  degrees  will  be 
found  satisfactory.  Sixty-five  degrees  or  above  on 
bright,  sunny  days  will  do  no  harm. 

Ventilation. — The  ventilators  should  be  opened  a  little 
every  day,  unless  the  weather  is  unusually  severe.  In 
warm,  bright  weather,  air  should  be  admitted  as  freely 
as  possible. 

Cultivation. — Small  weeders  used  between  the  rows 
are  beneficial  in  conserving  moisture  and  in  keeping  the 
soil  in  a  loose,  friable  condition.  In  wide,  ground  beds, 
a  five-prong  welder  attached  to  a  long  handle,  as  illus- 
trated in  Fig.  75,  will  be  found  a  most  excellent  tillage 
tool. 

Enemies. — The  radish,  when  grown  under  glass,  has 
very  few  enemies.  As  previously  stated,  damping-off 
fungi  may  attack  the  seedlings  in  beds  that  have  not  been 
sterilized.  The  green  aphis  is  the  most  important  insect 
pest  of  this  crop.  It  may  be  controlled  by  fumigating 
with  tobacco.  The  radish  is  more  susceptible  to  injury 
from  tobacco  smoke  than  is  lettuce.  The  safer  policy  is 
to  make  light  fumigations  rather  frequently. 

Frame  culture. — This  is  one  of  the  most  important 
crops  for  growing  in  hotbeds  and  frames.  (See  page  405.) 

Marketing. — The  proper  time  to  begin  pulling  the 
roots  depends  on  a  number  of  factors.  If  prices  are  very 
good  it  may  pay  to  begin  selling  them  when  they  are 


258  VEGETABLE   FORCING 

quite  small.  Ordinarily,  they  are  not  sold  until  they  are 
at  least  three-quarters  of  an  inch  in  diameter.  Market 
requirements  should  also  have  consideration. 

Ill-shaped  roots  should  be  discarded.  When  the  final 
pulling  is  made  on  a  given  area,  there  may  be  some  very 
small  roots,  which  should  be  thrown  away  or  packed  and 
sold  separately. 

Five  radishes  in  each  bunch  is  probably  the  most  com- 
mon number.  If  the  roots  are  very  small,  it  may  be 
necessary  to  tie  six  or  seven  in  a  bunch  in  order  to  meet 
the  requirement  of  the  market  to  be  supplied.  Some 
growers  put  10  to  12  in  a  bunch,  and  then  sell  at  prices 
proportionally  high.  This  saves  labor  in  tying,  washing 
and  packing. 

Raffia  is  commonly  used  for  tying,  though  many 
growers  use  light  cotton  twine.  The  radishes  are  im- 
proved in  appearance  by  clipping  off  the  slender  tips  of 
the  roots,  which  also  saves  time  in  washing.  Holding 
the  tied  bunches  in  running  water  under  a  spigot  may 
clean  the  roots  sufficiently  for  market ;  but  if  they  have 
been  grown  in  clay  soil,  the  use  of  a  scrubbing  brush  will 
be  necessary  to  remove  the  finer  particles  of  soil. 

The  radishes  may  be  packed  in  baskets  and  shallow 
crates  of  various  kinds.  Half-bushel  splint  baskets  are 
highly  satisfactory.  They  hold  from  eight  to  ten  dozen 
bunches.  If  the  inside  of  the  baskets  is  lined  with  two 
or  three  thicknesses  of  paper,  and  the  baskets,  after  the 
radishes  are  packed,  are  securely  wrapped  with  paper 
and  tied,  it  will  be  possible  to  ship  the  roots  in  severe 
winter  weather. 

Yields  and  returns. — About  two  dozen  good  radishes 
should  be  grown  on  each  square  foot  of  ground.  In  other 
words,  about  five  bunches  should  be  produced  to  the 
square  foot.  The  prices  are  so  variable  in  different  mar- 
kets and  at  different  seasons  of  the  year  that  it  is  im- 
possible to  give  figures  relating  to  returns  which  are  of 


RADISH  259 

much  value.  Prices  per  dozen  bunches  range  from  25 
cents  to  75  cents,  or  above,  for  large  bunches  of  fine 
roots.  A  good  crop  of  radishes  should  give  a  return  of  at 
least  12  cents  per  square  foot  of  bed  area. 


CHAPTER  XVII 
TOMATO 

History. — Practically  no  tomatoes  were  forced  in  this 
country  for  commercial  purposes  previous  to  1890.  A 
grower  here  and  there  would  have  a  few  dozen  or  per- 
haps a  few  hundred  plants,  but  tomato  forcing  did  not 
become  an  industry  of  real  importance  until  about  1900. 
Small  areas  were  planted  in  the  greenhouses  of  many  of 
the  agricultural  colleges  during  that  decade,  and  the 
bulletins  and  articles  published  relating  to  the  experi- 
ments attracted  the  attention  of  market  gardeners,  and 
no  doubt  influenced  many  of  them  to  make  small  plant- 
ings under  glass,  the  results  of  which  eventually  led  to 
the  forcing  of  the  crop  on  a  large  commercial  scale. 
Twenty-five  or  more  years  ago  a  few  bearing  tomato 
plants  were  often  seen  in  conservatories  of  the  wealthier 
classes,  but  the  idea  of  commercializing  the  proposition 
apparently  occurred  to  very  few  growers  before  1890. 

Importance. — As  stated  on  a  previous  page,  the  tomato 
is  now  one  of  the  three  most  important  vegetable-forcing 
crops.  Lettuce  ranks  first,  cucumber  second  and  the 
tomato  third,  and  the  tomato  is  increasing  in  importance 
every  year.  So  far  as  consumers  are  concerned,  it  is  a 
more  popular  vegetable  than  the  cucumber,  and  some 
growers  believe  that  it  will  ultimately  occupy  first  place 
in  commercial  importance. 

It  is  a  more  difficult  crop  to  grow  under  glass  than 
either  lettuce  or  cucumbers.  It  requires  much  more  heat 
than  lettuce  and  closer  attention  than  the  cucumber.  It 
is  regarded  by  many  as  a  hazardous  crop,  especially  in 
the  fall  and  winter.  Great  care  is  required  in  order  to 
avoid  serious  attacks  of  various  diseases.  The  white  fly, 
unless  the  houses  are  properly  fumigated  with  hydro- 

260 


TOMATO  261 

cyanic  gas,  may  practically  ruin  a  crop.  Skillful  water- 
ing, heating,,  ventilating  and  pollinating  are  required  to 
obtain  a  satisfactory  setting  of  fruit.  While  serious 
difficulties  may  exist,  there  are  now  many  growers  who 
are  experts  in  forcing  this  crop,  and  they  have  little  fear 
of  failure  because  they  are  thoroughly  conversant  with 
the  numerous  cultural  details  that  must  have  close 
attention. 

Southern  competition  should  be  considered  in  this 
connection.  The  tomato  pays  best  as  a  spring  forcing 
crop,  and  then  the  northern  greenhouse  product  invari- 
ably comes  into  competition  with  tomatoes  shipped  from 
Florida  and  other  southern  points.  While  forced  to- 
matoes, during  the  spring  and  early  summer,  un- 
doubtedly command  lower  prices  on  account  of  southern 
competition,  the  greenhouse  crop  is  so  superior  in  quality 
and  is  grown  at  a  cost  so  low  that  the  fruit  may  be  sold 
at  comparatively  low  prices,  say  10  cents  a  pound,  and 
still  leave  a  satisfactory  margin  of  profit. 

The  tomato  is  an  important  vegetable  for  forcing  be- 
cause it  fits  so  well  into  the  rotation  of  greenhouse  crops. 
Lettuce,  radishes  and  cauliflower  may  be  grown  during 
the  duller  weather  of  the  fall  and  winter,  and  tomatoes, 
set  in  the  beds  about  March  1,  will  come  into  bearing  the 
latter  part  of  May  and  continue  to  produce  until 
August  15.  The  spring  crop  is  not  so  difficult  to  grow, 
and  any  careful  gardener  may  be  reasonably  certain  of 
success. 

Hundreds  of  greenhouses  are  now  devoted  to  the 
forcing  of  tomatoes.  Some  of  the  ranges  occupy  several 
acres  of  land.  A  small  percentage  of  the  growers  pro- 
duce tomatoes  throughout  the  forcing  season.  Some 
grow  them  only  in  the  fall  and  occasionally  at  mid- 
winter, but  the  majority  find  that  it  is  most  satisfactory 
to  use  the  houses  for  cool  crops  until  spring  and  then  to 
plant  tomatoes,  which  are  marketed  mainly  during  the 
months  of  June  and  July. 


262  VEGETABLE  FORCING 

Pots  and  boxes. — In  the  early  years  of  tomato  forcing, 
the  plants  were  finally  shifted  to  8  to  10-inch  pots,  in 
which  they  were  grown  until  all  the  fruits  had  ripened. 
Large  pots  are  still  used  to  some  extent  in  conservatories. 
The  potted  plants,  laden  with  beautiful  pink  or  red  fruits, 
are  fully  as  attractive  as  many  plants  grown  solely  for 
ornamental  purposes.  It  is  more  difficult,  however,  to 
grow  good  tomatoes  in  pots  than  in  beds.  There  is  in- 
sufficient soil,  even  in  12-inch  pots,  for  the  best  results. 
The  soil  dries  out  rapidly  and  there  is  great  danger  of 
the  plants  being  stunted  or  checked  in  growth,  which 
invariably  reduces  the  yield.  Pots  are  convenient  for 
shifting  about  the  house  in  private  establishments,  and 
they  may  be  separated  as  much  as  necessary  in  order  to 
provide  ample  room  for  each  plant. 

Boxes  were  often  used  by  the  agricultural  experiment 
stations  from  1890  to  1900.  They  were  a  decided  ad- 
vantage over  pots  in  providing  more  soil  for  the  plants, 
and  they  could  also  be  conveniently  moved  from  place 
to  place.  Ordinarily,  they  were  10  inches  to  a  foot  deep. 
Cornell  University  used  boxes  that  were  18  inches 
square,  and  set  four  plants  in  each  box.  The  Tennessee 
station  obtained  fairly  satisfactory  yields  by  setting 
three  plants  in  a  box  1  by  1  by  3  feet  in  size.  It  is 
possible  to  get  better  results  in  boxes  than  in  pots,  but 
they  are  not  practicable  on  a  large  commercial  scale 
because  of  the  increased  cost  of  production  and  the 
smaller  yields  than  those  obtained  in  properly  prepared 
beds. 

Benches  vs.  ground  beds. — It  was  soon  discovered  by 
the  experiment  stations  as  well  as  by  practical  growers 
that  tomatoes  produced  larger  and  better  crops  on 
benches  than  in  pots  and  boxes.  In  the  first  place,  it  is 
much  cheaper  to  construct  benches  than  to  make  indi- 
vidual boxes  or  to  buy  the  required  number  of  large  pots. 
Furthermore,  the  soil  does  not  dry  out  so  rapidly  in  beds 
as  in  boxes. 


FIG.    P5.— TOMATOES    IN    KENNETT    SQUARE     (PA.)     HOUSE. 


264  VEGETABLE  FORCING 

For  many  years  New  England  growers  have  used 
raised  benches  for  the  forcing  of  tomatoes,  and  they  are 
now  extensively  employed  in  the  Kennett  Square  section 
of  Pennsylvania.  (See  Fig.  85.)  There  is  a  disposition, 
however,  among  growers  in  all  sections  to  abandon  the 
use  of  benches  and  to  plant  in  solid  ground  beds,  except 
when  the  crop  is  grown  during  the  winter  months.  In 
the  Ohio  and  Irondequoit  (N.  Y.)  vegetable-forcing  dis- 
tricts, ground  beds  are  used  almost  exclusively,  but  the 
tomato,  in  these  sections,  is  forced  mainly  as  a  spring 
crop.  The  great  barrier  to  the  use  of  benches  in  any 
locality  is  their  cost  of  construction  and  maintenance. 

Leaving  the  expense  factor  out  of  consideration,  what 
are  the  merits  of  benches  as  compared  with  ground  beds 
for  the  forcing  of  tomatoes?  The  tomato  is  a  plant  that 
requires  a  large  amount  of  heat.  For  this  reason,  the 
plants  grow  more  rapidly  on  benches  with  bottom  heat 
than  they  do  in  ground  beds.  There  is  a  difference  of  10 
days  to  two  weeks  in  the  maturity  of  the  crop,  if  grown 
at  midwinter.  Even  the  spring  crop  will  reach  the  ripen- 
ing period  quicker  if  there  is  bottom  heat.  On  the  other 
hand,  it  is  claimed  by  experienced  growers  that  total 
yields  are  greater  from  ground  beds,  so  that  earliness  in 
the  ripening  of  fruit  from  the  benched  plants  is  not  all 
gain.  It  is  more  difficult  to  properly  water  the  benches  so 
that  the  soil  throughout  is  as  moist  as  it  should  be,  and 
this  objection  is  made  by  growers  who  prefer  ground 
beds.  When  the  soil  in  the  benches  is  watered  by  sub- 
irrigation,  it  is  an  ideal  system,  especially  during  the  dull 
winter  months.  The  advantages  of  benches  provided 
with  sub-irrigation  lines  should  be  considered,  and  it  is 
possible  that  this  method  will  be  more  generally  used 
when  it  is  better  understood. 

For  the  spring  crop,  ground  beds  are  entirely  satis- 
factory. It  is  a  simple  matter  to  maintain  proper  soil 
moisture  conditions  in  them,  and  the  plants  are  easily 


TOMATO  265 

reached  for  the  pruning,  tying,  spraying  and  harvesting 
of  the  fruit. 

Varieties  of  tomatoes  which  are  used  for  forcing  differ 
widely  in  habit  of  growth  and  character  of  fruit.  It  can- 
not be  said  that  any  variety  in  cultivation  is  ideal  even 
for  any  one  market  or  section  of  the  country,  for,  while 
we  have  excellent  sorts,  there  is  much  that  should  be 
done  to  improve  them,  and  the  progress  being  made  in 
this  direction  is  exceedingly  encouraging. 

In  the  selection  of  a  variety  for  forcing,  the  first  factor 
to  consider  is  the  plant.  Has  it  the  ability  to  mature  a 
heavy  crop?  This  question  is  fundamental  in  impor- 
tance. Generally  speaking,  plants  with  short  internodes 
are  the  most  prolific.  They  bear  the  first  clusters  of 
fruit  near  the  surface  of  the  ground  and  a  maximum 
number  of  clusters  is  produced  on  plants  of  a  given 
height.  The  foliage  of  the  plants  should  be  highly  re- 
sistant to  disease.  In  this  respect,  there  is  abundant 
opportunity  for  improvement.  In  the  matter  of  area  or 
extent  of  leaf  surface,  there  is  some  difference  of  opinion 
as  to  what  is  best.  Theoretically,  it  would  seem  that 
plants  with  small  leaves  or  sparse  foliage  would  be  most 
suitable  for  greenhouse  culture,  because  such  plants 
interfere  the  least  in  admitting  light  and  in  securing  free 
circulation  of  air.  In  practice,  however,  most  growers 
pride  themselves  upon  the  vigor  and  even  the  size  of  the 
leaves.  The  writer  has  seen  expert  growers  handle  large, 
healthy,  green  leaves  with  as  much  delight  as  a  stockman 
would  fondle  a  pet  calf.  Abundant  foliage  is  apparently 
essential  in  the  production  of  large,  well-ripened  fruit. 

English  varieties,  such  as  Comet,  produce  more  to- 
matoes in  a  cluster  than  do  American  varieties,  such  as 
the  Globe.  This  tendency  to  set  a  very  large  number  of 
fruits  may  require  a  certain  amount  of  thinning  in  order 
to  obtain  specimens  of  marketable  size. 

Earliness  is  an  important  factor.     If  a  certain  variety 


266  VEGETABLE  FORCING 

will  mature  just  as  large  and  as  good  a  crop  in  several 
weeks  less  time  than  a  later  variety,  the  cost  of  produc- 
tion will  be  materially  less  and  profits  proportionately 
larger.  With  an  early-maturing  variety,  the  house  can 
be  used  later  in  the  spring  for  lettuce  or  radishes,  and 
have  sufficient  time  to  mature  tomatoes  for  the  June  and 
July  markets. 

When  tomatoes  are  cheap,  the  markets  will  take  fruits 
of  large  size,  but  when  they  retail  at  30  cents  or  more  a 
pound,  small  specimens  are  desired.  At  midwinter,  when 
maximum  prices  prevail,  the  fruits  are  generally  used  for 
salad,  and  usually  cut  into  thin  slices.  The  tendency, 
therefore,  is  to  grow  fruits  that  range  from  three  to  four 
ounces  in  weight  for  winter  sales  and  larger  sizes  for  the 
fall  and  early  summer  trade.  When  tomatoes  are  selling 
at  8  to  12  cents  a  pound  wholesale,  it  is  seldom  that 
there  is  any  complaint  about  their  being  too  large.  Some 
growers  select  varieties  which,  under  ordinary  condi- 
tions, yield  fruit  of  small  size,  but  by  liberal  fertilizing 
and  the  best  cultural  conditions  produce  specimens  that 
are  medium  to  large  in  size.  It  is  especially  important 
that  the  fruits  run  uniform  in  size. 

The  most  popular  forcing  varieties  produce  globular 
fruits.  They  should  be  regular  in  shape  and  free  from 
sutures.  The  color  is  almost  wholly  a  matter  of  market 
preference.  Most  markets  prefer  bright  red  tomatoes, 
though  there  are  many  exceptions.  The  brilliant  scarlet 
shades  are  somewhat  more  showy  than  the  pink  or 
purple  colors.  The  flesh  should  be  firm,  tender,  fine  in 
texture,  juicy  and  of  good  quality.  The  skin  should  not 
be  subject  to  cracking. 

The  testing  of  varieties  is  such  a  simple  proposition 
that  every  commercial  grower  should  satisfy  himself  by 
tests  in  his  own  houses  that  he  is  using  the  variety  which 
is  best  for  his  particular  market  and  conditions.  He 
should  be  on  the  alert  for  improved  varieties  or  strains, 


TOMATO  267 

small  plantings  of  which  should  be  made  to  determine 
whether  they  are  really  superior  to  the  variety  which  is 
being  grown  on  a  large  scale. 

There  are  two  general  classes  of  tomatoes — the  Eng- 
lish and  the  American — grown  in  the  greenhouses  of  this 
country.  The  English  varieties  are  typical  forcing  to- 
matoes, used  wholly  for  forcing  purposes  in  England, 
where  climatic  conditions  are  unsuitable  for  growing  the 
crop  out  of  doors.  The  leaves  of  English  varieties  are 
smaller  than  the  leaves  of  American  sorts.  English 
varieties  also  differ  from  our  common  sorts  in  setting  a 
larger  number  of  fruits  to  the  cluster,  and  the  fruits  are 
smaller  and  generally  more  uniform  in  size,  especially  if 
the  clusters  are  thinned.  The  size  of  certain  English 
varieties,  grown  in  this  country,  has  been  materially  in- 
creased by  selection. 

The  following  varieties  are  the  best  known  among 
American  growers  of  greenhouse  tomatoes : 

Beauty. — An  American  tomato  that  is  largely  grown 
as  a  spring  crop  in  Ohio.  The  Ohio  station  has  found 
this  to  be  a  most  excellent  forcing  variety.  The  plants 
are  vigorous  and  prolific.  The  fruit  is  pink,  large,  solid 
and  of  excellent  quality. 

Best  of  All. — An  English  variety  the  fruits  of  which 
are  somewhat  larger  than  ordinary  strains  of  Comet,  but 
it  is  not  so  productive. 

Bonny  Best  (Fig.  86)  is  probably  the  most  generally 
and  the  most  extensively  grown  of  the  American  class. 
It  is  universally  popular  for  fall  and  spring  culture,  and 
is  often  grown  at  midwinter.  The  fruits  are  larger  than 
Comet,  though  not  as  bright  scarlet  in  color.  The  plants 
are  vigorous  and  prolific.  Fruits  solid,  roundish,  oblate 
in  shape  and  very  good  in  quality.  The  earliness  of 
Bonny  Best  is  one  of  the  most  commendable  points. 

Carter's  Sunrise  is  a  small,  red,  English  variety  that 
ripens  several  weeks  earlier  than  Comet.  The  clusters 


268  VEGETABLE  FORCING 


Fig.  86. — Bonny  Best  tomato. 

are  very  large  and  often  shouldered,  and  thinning  is 
necessary  to  obtain  fruit  of  satisfactory  size.  The  liberal 
feeding  of  the  plants  of  this  variety  after  the  fruit  is  well 
set  is  also  an  advantage  in  increasing  the  size  of  the  fruit. 

Comet  (Fig.  87)  is  undoubtedly  the  best  known  of  the 
English  type.  The  plants  are  thrifty  in  growth  and 
highly  prolific.  The  roundish,  solid,  bright  red,  large- 
celled  fruits  are  exceedingly  attractive  and  their  quality 
is  excellent.  The  Comet  and  other  English  varieties  do 
not  require  as  much  attention  in  pollination  as  American 
varieties. 

Earliana,  the  most  largely  cultivated  of  early  American 
varieties,  is  not  extensively  grown  under  glass.  A  few 
growers  have  found  it  highly  profitable  for  spripg  cul- 
ture, but  the  comparatively  poor  quality  and  irregular 
shape  of  the  fruits  have  resulted  in  its  condemnation  by 
most  greenhouse  growers.  If  this  variety  is  used,  the 
best  strains  should  be  selected.  It  is  doubtful,  however, 
whether  Earliana  should  ever  be  chosen  in  preference  to 
Bonny  Best. 

Frogmore  is  a  peach-shaped  English  variety  of  good 


TOMATO  269 

size.  It  is  larger  than  Comet  and  is  recommended  for 
spring  planting. 

Globe  (Fig.  88)  is  a  popular,  pink  American  tomato, 
well  adapted  to  greenhouse  conditions.  It  is  quite  ex- 
tensively planted  for  the  spring  crop.  The  plants  are 
vigorous  and  very  prolific ;  fruits  large,  solid  and  of  good 
quality.  It  is  seldom  grown  as  a  winter  crop. 

Lorillard  is  one  of  the  oldest  of  the  American  varieties 


Fig.   87. — Comet  tomato. 

used  in  greenhouse  culture.  It  was  probably  the  most 
prominent  forcing  variety  from  1890  to  1900,  but  has  been 
almost  wholly  displaced  by  better  sorts.  It  is  not  nearly 
so  prolific  as  Bonny  Best  or  Comet. 

Magnus,  a  large-fruited  pink  tomato,  has  been  a 
favorite  among  Ohio  growers,  and  it  has  been  planted 
under  glass  to  some  extent  in  other  sections.  It  belongs 
to  the  potato  leaf  type,  so  that  the  foliage  is  much  more 
extensive  than  on  the  most  common  forcing  varieties. 
The  fruit  is  solid  and  of  excellent  quality. 

Peerless  (Fig.  89)  an  English  variety,  is  a  selection  of 
Lord  Roberts,  developed  by  Chauncey  West  of  Ironde- 


270 


VEGETABLE  FORCING 


quoit,  N.  Y.,  about  1908.  It  is  preferred  to  Comet  by 
some  of  the  most  successful  and  extensive  growers.  The 
fruit  is  borne  in  large  clusters,  and  the  individual  speci- 
mens are  medium  to  large,  solid  and  of  superior  quality. 
It  is  one  of  the  most  satisfactory  red  tomatoes,  suitable 
for  cultivation  at  any  time  during  the  forcing  season.  It 
requires  heavy  feeding. 

Stirling  Castle  is  an  old  English  variety  recommended 
by  a  few  American  growers.  The  fruits  are  smaller  than 
Comet,  and  thinning  and  high  fertility  are  necessary  to 
secure  specimens  of  satisfactory  size  for  commercial 
purposes. 

Stone,  a  well-known  very  late  American  variety,  has 
given  most  excellent  results  at  the  Ohio  station  as  well 
as  in  some  commercial  establishments.  However,  it  is 
losing  in  popularity  largely  because  of  its  extreme  late- 
ness. The  large,  solid,  beautiful  red  fruits  are  of  the  best 
quality. 

Numerous  miscellaneous  varieties   are  mentioned   in 


Fig.  88. — Globe  tomato. 


TOMATO 


271 


Fig.   89. — Peerless    tomato. 

the  literature  relating  to  tomato  forcing.  In  addition  to 
the  foregoing  list,  perhaps  the  following  are  the  most 
common :  June  Pink,  Combination,  Fordhook  First, 
Winter  Beauty,  Industry,  Success,  Mayflower,  Hummer, 
Alpha  Pink,  Burpee's  Earliest  Pink,  Eclipse,  Holmes's 
Supreme,  Dwarf  Champion  and  Hubert  Marvel. 

Soil. — A  great  many  different  soil  types  are  used  in 
growing  tomatoes  under  glass.  With  the  data  available 
it  cannot  be  said  that  larger  or  better  crops  can  be  grown 
in  one  soil,  referring  only  to  texture,  than  in  another. 
Unusually  heavy  greenhouse  crops  are  grown  in  the  very 
coarse  sandy  soils  of  Irondequoit.  Many  other  sections 
are  producing  heavy  yields  in  fine  sandy  soils,  and  some 
of  the  largest  yields  have  been  obtained  on  extremely 
heavy  clay  or  silt  soils.  The  general  advantages  of  the 
lighter  soils  have  been  recognized  in  Chapters  III,  V 
and  VI,  and  if  such  soils  are  available  for  the  forcing  of 
tomatoes,  they  should  be  chosen  in  preference  to  heavy 
soils,  other  factors  being  equal.  It  is  unmistakably  true 


272  VEGETABLE  FORCING 

that  any  soil  suitable  for  agricultural  purposes  will,  when 
properly  prepared  and  cultivated,  produce  a  satisfactory 
crop  of  greenhouse  tomatoes. 

Fertilizing. — Experienced  growers  agree  on  the  ne- 
cessity of  liberal  feeding  in  order  to  obtain  satisfactory 
yields  of  greenhouse  tomatoes.  Impoverished  soils  in- 
variably produce  weak,  spindling  plants  which  fail  to 
bear  profitable  crops.  On  such  plants  the  number  of 
fruits  is  limited  and  the  individual  specimens  are  small 
in  size  and  inferior  in  quality.  High  fertility  is  essential 
from  every  standpoint. 

While  liberal  feeding  is  necessary,  it  is  important  to 
maintain  a  proper  balance  in  the  elements  applied.  An 
excessive  amount  of  nitrogen  and  a  deficiency  of  potash 
and  phosphoric  acid  will  be  certain  to  result  in  a  rank 
growth  of  low  production  plants.  On  the  other  hand,  a 
superabundance  of  the  mineral  elements  and  very  little 
nitrogen  will  result  in  light  stems  and  small  leaves  and 
solid  but  undersized  fruit.  There  can  be  no  shortage  in 
any  of  the  elements  without  affecting  the  yield  as  well 
as  the  quality  of  the  crop. 

Jenkins  and  Briton,  of  the  Connecticut  Experiment 
Station,  found  that  tomato  plants  on  100  square  feet  of 
bench  space  assimilated,  from  February  1  to  July  1,  226 
grams  of  nitrogen,  74  grams  of  phosphoric  acid  and  391 
grams  of  potash.  To  meet  these  requirements  it  would 
be  necessary  to  apply  3  pounds  10  ounces  of  nitrate 
of  soda,  1  pound  of  boneblack  and  1  pound  12  ounces 
of  muriate  of  potash.  It  is  customary,  however,  to  apply 
more  than  enough  food  to  merely  meet  the  needs  of  the 
plants  because  all  of  it  is  not  accessible  to  the  roots.  Any 
surplus  at  the  close  of  any  one  harvest  will  remain  for 
succeeding  crops,  except  that  there  is  constant  loss  of 
nitrogen  by  volatilization. 

Comparatively  few  gardeners  use  commercial  fertilizers 
at  all  in  the  growing  of  the  greenhouse  crop.  They  claim 
that  when  stable  manure  is  used  in  sufficient  quantity  to 


274  VEGETABLE  FORCING 

maintain  proper  physical  conditions  of  the  soil,  there  will 
be  as  much  of  the  various  elements  of  plant  food  as  the 
crop  can  utilize.  Many  of  the  heaviest  crops  are  grown 
year  after  year  without  employing  chemicals  or  any  kind 
of  commercial  fertilizer.  Other  growers  claim  that  light 
dressings  of  complete  fertilizers  have  increased  yields  as 
well  as  profits.  A  fairly  common  practice  is  to  use  a  little 
nitrate  of  soda  about  each  plant  after  the  fruit  is  set. 
Others  feed  the  plants  with  liquid  manure  after  the  fruit 
is  set.  This  method  is  used  in  the  Kennett  Square  sec- 
tion of  Pennsylvania.  Mulching  with  stable  manure,  as 
described  on  page  78,  has  practically  the  same  effect. 
Bone  meal,  wood  ashes,  tankage  and  sheep  manure  are 
often  used  in  the  smaller  forcing  establishments. 

Soil  preparation. — The  general  remarks  on  Soil  Prep- 
aration, Chapter  V,  and  Soil  Sterilization,  Chapter  VI, 
apply  to  the  fitting  of  beds  for  growing  tomatoes.  If 
tomatoes  only  are  grown  in  the  houses  year  after  year, 
without  any  rotation,  it  will  be  an  advantage  to  change 
the  soil  at  least  every  fifth  year,  though  with  thorough 
steam  sterilization  there  may  be  continuous  cropping  for 
a  long  term  of  years.  Whenever  benches  are  used,  as  in 
the  Kennett  Square  district  of  Pennsylvania,  the  usual 
plan  is  to  change  the  soil  every  year  or  two.  In  most  of 
the  large  establishments,  containing  an  acre  or  more  of 
glass,  and  where  ground  beds  are  employed,  the  common- 
est plan  is  to  apply  liberal  amounts  of  manure  for  lettuce 
during  the  fall  and  winter  and  then  to  use  no  manure  for 
the  tomatoes,  which  are  generally  grown  as  a  spring 
crop,  except  the  manure  mulch,  which  is  as  a  rule  applied 
after  most  of  the  fruit  is  set.  Any  soil,  however,  which 
needs  additional  plant  food  or  organic  matter  should  be 
enriched  by  spading  or  plowing  in  well-decayed  manure 
before  the  beds  are  planted  with  tomatoes. 

In  the  sections  near  Philadelphia  where  mushrooms 
are  grown  on  a  large  scale  it  is  usual  to  apply  about  4 
inches  of  manure  (see  page  424  for  composition),  which 


TOMATO  275 

has  been  used  for  growing  mushrooms,  to  suitable  areas 
in  the  field.  The  land  is  plowed  a  few  times  during  the 
summer  and  the  soil  placed  on  raised  beds  in  the  fall  for 
the  culture  of  tomatoes  and  carnations.  Bone  meal  is 
generally  mixed  with  the  soil  when  it  is  transferred  to 
the  houses,  and  the  tomato  plants  are  fed  with  liquid 
manure  after  the  fruit  is  set. 

Seed. — Very  few  vegetables  are  more  susceptible  to 
improvement  from  seed  selection  than  the  tomato. 
Numerous  examples  could  be  cited  of  growers,  who, 
being  pleased  with  certain  characteristics  of  perhaps  well- 
known  varieties,  have  made  decided  progress  in  improv- 
ing them  by  means  of  careful  seed  selection.  This  state- 
ment applies  to  Bonny  Best,  Lord  Roberts,  Comet  and 
other  prominent  greenhouse  varieties.  In  some  instances, 
the  improvement  has  been  so  marked  that  a  new  name 
has  been  given  the  superior  strain,  as  when  Peerless  was 
developed  as  a  selection  of  Lord  Roberts. 

Seedsmen  often  make  a  specialty  of  varieties  suitable 
for  forcing  purposes.  In  some  instances  the  strains  are 
most  excellent  and  growers  would  not  make  a  mistake  by 
purchasing  such  seed.  Scores  of  growers,  however,  do 
not  care  to  take  any  risks  in  the  matter  of  planting  the 
best  seed,  so  that  there  is  a  general  and  an  increasing 
tendency  to  make  careful  selections  from  plants  in  their 
own  greenhouses.  When  an  unusually  good  crop  is  pro- 
duced it  is  possible  to  save  enough  seed  from  robust, 
productive  plants  to  last  five  years  or  even  longer,  so  that 
it  is  unnecessary  to  give  this  matter  attention  every  year. 

The  grower  should  establish  high  ideals  with  reference 
to  the  most  important  points — such  as  color,  size  and  shape 
of  fruit,  productiveness  of  the  plants  and  their  ability  to 
resist  disease — and  the  desired  characteristics  should  be 
kept  constantly  in  mind  in  selecting  fruit  for  seed  pur- 
poses. 

Cuttings. — Tomato  plants  are  easily  propagated  by 
means  of  cuttings.  They  may  be  made  of  any  convenient 


276  VEGETABLE   FORCING 

size,  preferably  short  and  stocky,  and  rooted  in  sharp 
sand.  If  a  little  bottom  heat  is  provided,  the  cuttings 
will  root  in  five  or  six  days,  when  they  can  be  potted  and 
grown  to  proper  size  for  planting  in  the  beds.  The  few 
experiments  which  have  been  made  seem  to  indicate  that 
plants  propagated  from  June  cuttings  are  not  as  prolific 
as  those  grown  from  seed,  so  that  no  advantage  in  gen- 
eral cropping  is  gained  by  using  cuttings.  There  are  in- 
stances, however,  when  it  is  desirable  to  perpetuate  a 
stock  of  choice  plants,  and  this  can  be  done  only  by  means 
of  cuttings.  If  an  unusually  fine  plant  is  found,  seed 
should  be  saved  from  it  for  testing,  and  additional  trials 
may  be  made  of  the  plants  rooted  from  cuttings. 

Plants  large  enough  for  the  beds  or  benches  may  be 
grown  in  much  less  time  from  cuttings  than  from  seed, 
but  this  is  probably  of  no  value  from  a  commercial  view- 
point, because  seedlings  require  so  little  space  until  they 
are  large  enough  for  potting.  It  is  simply  a  question'  of 
sowing  early  enough  to  grow  plants  of  proper  size  for 
planting  in  the  beds  at  the  desired  time. 

Starting  plants. — The  proper  time  of  sowing  depends 
upon  a  number  of  factors:  (1)  Earliness  of  the  variety. 
Some  varieties  require  nearly  a  month  longer  than  others 
to  mature  fruit.  Bonny  Best  sown  July  1  in  central 
Pennsylvania  produced  a  few  ripe  specimens  October  11. 
Stone  probably  would  have  produced  no  ripe  tomatoes 
before  November  1.  (2)  Amount  of  sunshine.  There  is 
more  bright,  sunny  weather  in  some  sections  than  in 
others,  and  there  is  much  more  sunshine  late  in  the  winter 
and  spring  than  during  the  fall  and  early  winter.  Prob- 
ably four  or  five  weeks  more  time  would  be  required  to 
mature  Bonny  Best  sown  November  15  than  for  the  same 
variety  started  February  1.  (3)  Temperature  of  the 
house.  High  temperatures,  especially  when  the  plants 
are  young,  necessarily  shorten  the  time  from  seed  sowing 
until  the  ripening  period.  (4)  Market  demands.  This 
question  should  have  most  careful  consideration.  For 


FIG.    91.— ECLIPSE    X    EARLIANA    TOMATOES    AT 
THE    NEW   HAMPSHIRE   EXPERIMENT  STATION. 


278  VEGETABLE  FORCING 

example,  prices  for  the  spring  crop  are  always  higher 
early  in  June  than  later  in  the  month,  and  it  is  important 
to  sow  in  ample  time  to  mature  the  crop  so  as  to  obtain 
the  highest  prices. 

Seed  for  the  fall  crop  is  usually  sown  from  June  20  to 
July  1.  A  few  growers  sow  from  July  15  to  August  1, 
but  this  is  regarded  as  very  late  sowing.  There  should 
be  special  reasons  for  starting  the  fall  crop  later  than 
July  1.  The  fruit  should  be  well  set  by  the  middle  of 
November,  when  there  is  usually  much  more  cloudy 
weather  than  earlier  in  the  fall.  Seed  for  the  winter  crop 
may  be  sown  in  succession  from  August  15  to  No- 
vember 15. 

There  is  considerable  difference  of  opinion  regarding 
the  best  time  to  sow  for  the  spring  crop.  Many  of  the 
most  extensive  growers  sow  from  January  1  to  15. 
Others,  who  use  the  earlier  varieties,  such  as  Bonny  Best 
and  Comet,  sow  from  January  15  to  February  1.  A  promi- 
nent Irondequoit  (N.  Y.)  grower  sows  Peerless  from 
January  15  to  February  1.  Many  growers  aim  to  set  the 
plants  in  the  permanent  beds  about  March  1,  and  such 
plants  will  begin  to  ripen  fruit  the  latter  part  of  May  or 
early  in  June.  The  earliest  varieties  will  give  very  good 
results  if  not  planted  in  the  beds  until  March  15  or  even 
April  1. 

The  commonest  practice  is  to  sow  the  seed  in  flats  or 
beds,  as  explained  in  Chapter  IX.  There  should  be  ample 
space  between  the  rows  and  the  seed  should  be  sown 
thinly  so  as  to  induce  the  growth  of  stocky  plants.  It  is 
desirable  to  transplant  the  seedlings  before  they  show  any 
tendency  to  become  spindling.  Ordinarily,  the  first  shift 
can  be  made  in  three  weeks  from  the  date  of  sowing.  The 
plants  are  generally  set  in  flats  or  beds  and  spaced  from 

2  to  3  inches  apart.    When  they  begin  to  crowd,  a  second 
shift  is  made  to  3^  or  4-inch  pots.    Some  growers  make 
four  shifts,  the  first  into  flats  or  small  pots,  the  second  into 

3  or  3^-inch  pots  and  the  third  into  5-inch  pots,  and 


TOMATO  279 

finally  into  the  permanent  beds.  The  most  extensive  com- 
mercial growers  seldom  make  more  than  three  shifts, 
including  the  final  transplanting  into  the  beds. 

An  extensive  grower  at  Cleveland,  Ohio,  sows  in  beds 
and  then  sets  two  plants  in  a  quart  berry  basket;  these 
are  ultimately  set,  basket  and  all,  in  the  ground  beds.  It 
is  claimed  that  the  results  are  just  as  satisfactory  as  when 
pots  are  employed  and  that  the  expense  in  starting  the 
plants  is  less. 

The  utmost  care  should  be  exercised  in  the  growing  of 
strong,  robust  plants.  They  should  not  be  permitted  to 
become  pot-bound  at  any  time.  Careful  watering  and 
ventilation  are  of  urgent  importance. 

Planting  distances. — There  is  the  greatest  diversity  of 
practice  in  the  planting  distances  adopted  by  different 
growers.  Some  tests  have  been  made  at  the  experiment 
stations,  but  the  results  with  different  varieties  under 
variable  conditions  are  so  contradictory  that  conclusions 
of  real  value  cannot  be  drawn. 

Close  planting  undoubtedly  results  in  smaller  tomatoes 
and  smaller  yields  to  the  plant,  but  not  necessarily  smaller 
yields  per  square  foot.  The  tendency  of  commercial 
growers,  however,  is  to  become  more  liberal  in  the  amount 
of  space  between  rows,  which  is  a  decided  advantage  in 
caring  for  the  plants  and  in  harvesting  the  fruit.  For- 
merly the  most  common  practice  was  to  plant  16  by  18, 
18  by  18,  20  by  24  or  24  by  24  inches.  Now  .the  more 
frequent  plan  is  to  allow  2^  to  4  feet  between  rows  and 
to  set  the  plants  a  foot  to  18  inches  apart  in  the  row. 
For  example,  one  of  the  most  successful  growers  at  Iron- 
dequoit  has  only  seven  rows  in  a  house  30  feet  wide,  and 
the  plants  are  18  inches  apart  in  the  rows.  A  prominent 
Cleveland  grower  allows  3  feet  between  rows,  and  berry 
baskets,  each  containing  two  plants,  are  set  at  intervals 
of  27  inches.  A  well-known  grower  in  Western  Pennsyl- 
vania plants  3  feet  by  15  inches ;  an  Erie,  Pa.,  grower  3  feet 
by  12  inches,  a  Massachusetts  grower  3  feet  by  15  inches. 


280  VEGETABLE  FORCING 

When  grown  with  carnations,  a  common  distance  is 
20  by  20,  or  three  rows  on  benches  4  feet  wide.  Another 
well-known  Ohio  grower  plants  4  by  1  foot  apart,  and  a 
Grand  Rapids  grower  3^  by  1.  Some  growers  are  pleased 
with  the  following  hexagonal  plan  which  gives  each  plant 
the  maximum  amount  of  space  in  every  direction : 

X  X  X  X  X 


Planting. — As  previously  stated  in  this  chapter,  the 
plants  should  not  be  allowed  to  become  pot-bound  before 
they  are  shifted  or  transferred  to  the  beds.  The  plants 
may  be  set  a  trifle  deeper  than  they  stood  in  the  pots,  and 
it  is  generally  desirable  to  water  the  beds  after  they  are 
filled  with  plants.  See  page  278  for  dates  on  which  to 
plant. 

Intercropping. — Tomato  plants  soon  develop  a  large 
amount  of  foliage  which  retards  the  development  of 
smaller  crops,  such  as  lettuce  and  radishes,  so  that  they 
are  not  very  well  adapted  to  companion  cropping,  except 
when  they  follow  carnations.  See  Chapter  XXI  for  data 
on  systems  of  cropping. 

Training. — When  tomatoes  are  produced  under  glass 
there  must  be  some  means  of  regulating  the  habit  of 
growth.  Numerous  experiments  have  been  made  with  a 
view  to  determining  the  best  system  of  training.  In 
most  of  the  trials,  the  plants  have  been  trained  to  one, 
two  and  three  stems,  respectively.  Perhaps  the  most 
extensive  work  along  this  line  was  conducted  by  the  New 
York  station.  Beach,  in  drawing  conclusions  in  Bul- 
letin 123,  states :  "Single-stem  training  (as  seen  in  Figs. 
90,  91  and  92)  is  clearly  superior  to  three-stem  training 
for  forcing  tomatoes  in  winter — in  this  climate.  The 
superiority  is  seen  in  the  larger  yield  of  early  ripening 


282  VEGETABLE  FORCING 

fruit  and  in  the  larger  total  yield.  There  is  but  slight 
difference  in  the  average  size  of  fruit  produced  under  the 
two  methods  of  training,  but  on  the  whole  the  fruits  of 
the  single-stem  plants  seem  to  be  slightly  the  larger." 

The  advantages  of  single-stem  training  over  two-stem 
training  are  not  so  marked,  and  yet  the  fact  that  prac- 
tically all  of  the  most  extensive  growers  of  forced  to- 
matoes use  the  single-stem  system  is  a  strong  testimony 
in  its  favor.  It  is  doubtful  whether  growers  are  ever 
justified  in  using  any  other  system  of  training.  It  is  the 
simplest  and  most  satisfactory  in  every  respect. 

There  are  various  ways  of  supporting  the  plants.  The 
commonest  is  to  tie  them  to  twine  or  cord  stretched  from 
the  base  of  the  plants  to  wires  or  rafters  above  the  plants. 
Many  growers  stretch  wires  above  each  row,  running  the 
full  length  of  the  house.  They  may  be  secured  at  the 
ends  in  any  convenient  way  and  fastened  with  staples  to 
the  rafters,  or  by  other  means  if  desired.  Sometimes 
wires  are  also  stretched  across  the  beds  at  the  surface  of 
the  ground,  but  they  interfere  with  tillage  and  are  an  un- 
necessary expense.  Twine  (binder  twine  is  excellent) 
looped  to  the  base  of  the  plants  and  tied  taut  to  the  wire 
above  will  be  very  satisfactory.  Waid  recommends  the 
use  of  "screw  wires"  of  No.  10  or  11  wire  which  are 
screwed  4  or  5  inches  into  the  soil  close  to  each  plant. 
These  are  provided  with  a  loop  at  the  top  to  which  the 
twine  is  tied.  Waid  gives  the  following  description  in 
the  Market  Growers'  Journal  of  a  simple  device  for  the 
making  of  these  wire  screws  : 

"It  consists  of  a  piece  of  inch  and  a  quarter  pipe  about  6  inches 
long,  through  which  a  ^-inch  pipe  is  run,  extending  out  at  one 
end  far  enough  to  attach  a  handle,  and  at  the  other  about  5  inches. 
Two  holes  are  bored  in  the  smaller  pipe,  each  just  large  enough 
to  admit  the  wire.  One  hole  is  near  the  end  of  the  pipe  and  the 
other  about  4  inches  from  the  end  or  close  to  the  end  of  the  larger 
pipe.  The  larger  pipe  is  placed  in  a  vise  and  the  device  is  ready 
for  operation.  The  wire  is  cut  10  to  12  inches  in  length,  one  end 


TOMATO  283 

placed  in  the  hole  in  the  pipe  the  farthest  from  the  end.  Precaution 
must  be  taken  not  to  let  it  in  too  far,  or  it  will  be  troublesome  to 
get  the  wire  out  after  it  is  twisted.  The  handle  is  turned  backward 
with  one  hand  while  the  wire  is  held  firmly  against  the  pipe  with  the 
other.  Two  full  turns  of  the  handle  are  made,  and  the  wire  should 
be  guided  so  that  it  will  be  near  the  outer  end  of  the  smaller  pipe 
when  the  turns  have  been  made.  The  straight  end  of  the  wire  is 
then  turned  so  that  it  is  parallel  with  the  pipe.  The  other  end  of 
the  wire  is  then  extracted  from  the  hole  by  means  of  a  screw- 
driver. The  straight  end  of  the  wire  is  next  placed  in  the  hole  near 
the  end  of  the  pipe  and  the  handle  given  a  half  turn.  This  last 
move  makes  the  loop  to  the  wire  and  finishes  the  operation.  The 
reason  for  turning  the  handle  backwards  in  the  first  case  is  to  make 
the  wire  so  that  it  will  screw  into  the  soil  the  same  as  a  screw  turns 
into  wood.  If  the  handle  is  turned  forward  the  wire  will  have  to  be 
screwed  into  the  soil  backwards.  When  a  person  becomes  ac- 
customed to  making  the  wires  he  can  make  at  least  500  a  day." 

A  few  growers  prefer  to  use  very  thin  strips,  as  ex- 
plained for  cucumbers  on  page  399.  Others  have  found 
special  wire  trellises  highly  satisfactory.  They  may 
consist  of  five  to  seven  wires  running  lengthwise  of  the 
house  with  cross  wires  at  frequent  intervals.  The 
trellises  are  attached  or  hinged  to  pipe  purlins  above,  so 
that  they  can  be  swung  up  out  of  the  way  when  not  in 
use,  and  dropped  in  a  few  minutes  when  they  are  needed 
for  the  support  of  plants.  This  plan  is  most  commend- 
able in  every  particular.  An  important  advantage  of  the 
plan  is  that  jarring  the  trellis  to  which  the  plants  are  tied 
with  a  stick  at  mid-day  when  the  sun  is  shining  is  a  most 
effective  aid  to  pollination.  See  page  288. 

When  twine  supports  are  used,  it  is  customary  to  tie 
the  plants  at  about  four  points  with  raffia  or  coarse 
twine.  The  loops  should  be  made  as  far  as  possible 
below  the  nodes  of  the  plants,  in  order  to  provide  more 
perfect  support.  An  excellent  plan  is  to  coil  the  plant  as 
it  increases  in  height  about  the  twine,  when  it  is  unneces- 
sary to  make  so  many  ties. 

All  lateral  shoots  are  pinched  off,  when  they  are  very 


284  VEGETABLE  FORCING 

small,  with  the  thumb  and  finger.  The  plants  should  be 
looked  over  at  least  once  a  week  so  that  none  of  them 
will  attain  any  considerable  size  before  being  removed. 
When  the  plant  reaches  the  desired  height,  the  terminal 
is  pinched  off.  Most  growers  prefer  plants  that  are  6  to  7 
feet  high.  In  eastern  sections  they  are  sometimes  grown 
to  a  height  of  8  to  10  feet.  Alertness  is  required  to 
observe  all  the  lateral  shoots  and  to  avoid  pinching  off 
the  terminal  shoot  before  the  desired  height  of  the  plant 
has  been  secured. 

Growers  do  more  or  less  pruning  of  the  leaves.  This 
seems  to  be  an  advantage  when  the  growth  is  very  rank, 
but  it  is  a  matter  which  should  be  managed  with  extreme 
care.  Excessive  defoliation  is  certain  to  result  in  dimin- 
ished fruit  production.  When  the  lower  leaves  become 
badly  diseased,  they  should  be  promptly  removed  and 
destroyed. 

Watering. — Tomato  plants  require  an  abundance  of 
water,  and  this  is  especially  true  after  they  have  grown 
to  a  height  of  several  feet.  There  is  always  danger  of  in- 
sufficient water  being  applied  and  the  moisture  failing  to 
reach  the  bottom  of  the  beds.  In  very  heavy  soils  which 
do  not  contain  enough  organic  matter,  repeated  watering 
on  the  surface  of  the  ground  is  likely  to  compact  the  soil 
and  thus  prevent  the  percolation  of  the  water  to  the  full 
depth  of  the  beds.  This  is  one  of  the  main  arguments  for 
mulching  with  manure  or  watering  by  means  of  sub- 
irrigation.  When  the  supply  of  soil  moisture  is  insuffi- 
cient, blossom  end  rot  of  the  fruit  is  likely  to  occur,  the 
plants  will  not  be  thrifty  in  growth  and  the  fruits  will  be 
small.  While  an  abundance  of  moisture  is  absolutely 
necessary,  a  saturated  condition  of  the  soil  must  also  be 
avoided,  for  this  invariably  causes  the  growth  of  weak, 
spindling  plants  with  yellowish  leaves  and  low  fruit  pro- 
duction. Diseases  are  also  more  destructive  when  the 
soil  contains  too  much  water.  Over-watering  is  most 


TOMATO  285 

likely  to  occur  during  the  winter  months  when  there  is  so 
much  dark,  cloudy  weather.  During  the  bright  spring 
and  warm  summer  weather  an  enormous  amount  of 
water  can  be  applied  without  danger  of  injury.  At  this 
season  of  the  year  it  may  be  necessary  to  water  daily  or 
even  twice  a  day  under  certain  conditions. 

The  method  of  watering  should  have  careful  considera- 
tion. Watering  has  a  very  close  relation  to  the  question 
of  pollination.  (Page  288.)  A  dry  atmosphere  is  most 
favorable  to  the  discharge  of  pollen  and  the  setting  of  a 
maximum  number  of  fruits.  It  is  also  important  to  pro- 
tect the  flowers  from  water,  which  may  wash  away  the 
pollen  grains  and  thus  result  in  a  small  setting  of  fruit. 
The  foliage,  too,  when  it  becomes  wet,  is  more  sus- 
ceptible to  fungous  diseases  of  various  kinds.  Overhead 
watering  is  used  to  a  considerable  extent  in  growing 
tomatoes,  but  it  is  readily  seen  that  the  arguments  are  in 
favor  of  applying  water  with  a  hose,  care  being  taken  to 
keep  the  plants  as  dry  as  possible.  From  the  standpoint 
of  saving  labor,  avoiding  diseases  and  securing  a  heavy 
crop  of  fruit,  sub-irrigation  seems  to  possess  special  ad- 
vantages. Experiments  made  by  Waid  in  a  two-year  test 
on  raised  benches  at  the  Ohio  station  gave  the  following 
results : 


Method  of 
watering 

Surfa.cc  watered 

Yield  per                    Av.  sizes       Amount  of 
square  foot                    of  fruit        rot  per  sq.  ft. 
Ibs.                   oz                       oz                    oz 

1                 150                 5.0                 4.7 

Sub-irrierated    - 

2                   4.5                 5.9                 1.9 

"With  two  houses,  each  having  960  square  feet  of  bench  space 
planted  to  tomatoes  and  both  treated  alike  except  in  the  manner  of 
watering,  the  sub-irrigated  house  would  yield,  calculating  the  yield 
according  to  the  above  table,  330  pounds  more  of  tomatoes  than  the 
surface-watered  house.  The  surface-watered  house  would  give,  on 
the  other  hand,  168  pounds  more  of  fruit  affected  by  rot  than  the 
sub-irrigated  house." 

Temperature. — The  night  temperature  for  tomatoes 
should  never  be  lower  than  60  degrees,  and  the  tempera- 


286  VEGETABLE  FORCING 

• 

ture  on  cloudy  days  during  the  winter  should  be  about  70 
degrees.  In  warm,  bright,  sunny  weather,  no  injury  will 
result  from  very  high  temperatures.  It  is  a  common 
occurrence  for  the  temperature  to  rise  in  the  houses  to 
over  100  degrees  during  the  months  of  June  and  July. 

Ventilation. — As  previously  stated  (page  166),  the 
houses  should  be  ventilated  as  freely  as  weather  condi- 
tions will  permit.  Some  fresh  air  should  be  admitted 
every  day,  even  in  the  coldest  weather.  In  warm 
weather  it  is  desirable  to  keep  the  ventilators  open  all 
night.  During  the  late  spring  and  summer  months  doors 
and  ventilators  should  be  opened  full  width  unless 
storms  make  it  necessary  to  close  them  for  a  short  time. 
Thorough  ventilation  is  exceedingly  important  in  the 
control  of  fungous  diseases.  It  is  also  an  aid  in  the 
pollination  of  the  flowers. 

Cultivation. — When  the  beds  are  not  mulched  it  is  im- 
portant to  cultivate  the  soil  as  often  as  may  be  necessary 
to  keep  the  surface  in  a  loose,  friable  condition.  When 
2*/2  feet  or  more  of  space  is  allowed  between  rows,  it  is 
possible  to  till  the  soil  with  a  wheel  hoe.  Tillage  must 
not  be  deep  enough  to  injure  the  roots  of  the  plants. 

Mulching. — The  majority  of  greenhouse  growers  of 
tomatoes  mulch  the  beds  with  horse  manure.  Among  the 
advantages  which  may  be  mentioned  are  the  conserva- 
tion of  soil  moisture,  prevention  of  weed  growth,  saving 
of  labor  in  cultivating,  saving  of  labor  in  watering  so 
frequently,  and  the  feeding  of  the  plants  by  food  leached 
from  the  manure  after  every  surface  application  of  water. 
Unless  the  soil  is  excessively  rich  in  nitrogen,  mulching 
with  manure  is  probably  always  beneficial,  and  should 
there  be  a  surplus  of  this  element  in  the  soil,  cut  straw 
might  be  substituted. 

Mulching  is  most  beneficial  when  surface  watering  is 
practiced,  but  it  is  also  an  advantage  with  sub-irrigation. 
Almost  any  kind  of  organic  material  may  be  used  for 


TOMATO  287 

mulching,  but  fresh  horse  manure  is  generally  employed. 
Care  should  be  exercised  in  order  to  avoid  burning  the 
leaves  with  ammonia  that  may  escape  from  hot  manure. 
Such  injury  may  be  prevented  by  spreading  the  manure 
in  thin  layers  until  it  is  cool,  or  it  may  be  soaked  with 
water  immediately  after  it  is  applied  to  the  beds.  A 
depth  of  3  or  4  inches  is  necessary  for  the  best  results. 
Mulching  is  most  commonly  employed  with  the  spring 
crop.  If  surface  watering  is  practiced,  most  of  the  ma- 
nure will  be  sufficiently  decayed  by  midsummer  to  spade 
or  plow  into  the  soil  preparatory  to  the  fall  crop  of 
lettuce  or  cauliflower. 

An  experiment  made  at  the  Ohio  station  demonstrated 
the  superiority  of  a  strawy  manure  mulch  over  straw 
alone.  There  were  two  plots,  each  120  square  feet  in 
area,  and  28  plants  were  set  in  each  plot.  The  results 
were  as  follows : 

PLOT  1 — MANURE  MULCH 

Variety                                                 Number  of  Weight 

fruits  Ibs. 

Magnus 326  102 

Stone    299  104 

Beauty 256  72 


881  278 
PLOT  2 — STRAW  MULCH 

Magnus  234  63 

Stone 234  75 

Beauty 234  76 

702  214 

The  plants  in  the  manure-mulched  beds  averaged 
about  9*4  pounds  each,  while  those  in  the  straw-mulched 
beds  averaged  about  7^4  pounds  to  the  plant. 

There  is  considerable  difference  of  opinion  among 
growers  concerning  the  proper  time  to  apply  a  mulch. 
If  straw  is  used,  there  can  be  no  objection  to  putting  it 
on  immediately  after  the  plants  are  set,  and  some  grow- 
ers who  use  manure,  mulch  at  this  time.  It  is  claimed  by 


288  VEGETABLE  FORCING 

others  that  the  danger  of  early  mulching,  causing  ex- 
cessive plant  growth  with  more  or  less  hindrance  to  fruit 
development,  makes  it  desirable  to  defer  this  operation 
until  at  least  three  clusters  of  fruit  are  set.  The  latter 
policy  is  certainly  safe  and  is  probably  followed  by  the 
majority  of  growers.  It  is  also  believed  by  some  growers 
that  a  mulch  kept  constantly  wet  from  the  first  promotes 
the  development  and  dissemination  of  diseases.  But  this 
is  not  so  likely  to  occur  if  the  mulch  is  applied  late  in  the 
season  when  there  is  warm,  sunny  weather. 

Pollinating. — The  tomato  grower  should  fully  under- 
stand the  function  of  the  various  parts  of  the  flower. 
The  green,  starlike  outer  portion  is  the  calyx  and  its 
separate  parts  are  known  as  the  sepals.  Apparently,  the 
only  function  of  this  organ,  but  a  very  important  one,  is 
to  furnish  protection  to  the  young,  tender  buds.  The 
yellow  corollas,  formed  of  separate  parts  called  "petals," 
which  in  many  flowers  attract  certain  insects,  do  not 
seem  to  have  any  particular  functional  value  in  the  cul- 
ture of  tomatoes,  because  bees  refuse  to  visit  them  and 
thus  to  convey  pollen  from  flower  to  flower.  The 
stamens,  the  next  set  of  organs,  form  a  tube  which  in- 
closes the  pistil.  They  are  the  male  portions  of  the 
flower,  and  the  anthers,  borne  in  a  column  surrounding 
the  pistil,  produce  the  pollen  grains  which  fertilize  the 
central  or  female  organ,  the  pistil.  The  top  of  the  pistil 
is  called  the  stigma,  and  this  is  larger  than  the  pedicle 
below,  which  is  called  the  style.  The  base  of  the  pistil 
is  known  as  the  ovary,  which  contains  the  ovules  in 
which  the  seeds  develop. 

As  the  flower  matures,  the  pistil  elongates  until  it 
generally  protrudes  above  the  stamens.  The  minute, 
dust-like  pollen  grains  then  ripen  and,  under  favorable 
atmospheric  conditions,  are  discharged  into  the  air,  when 
some  of  them  will  lodge  on  and  adhere  to  the  sticky  and 
moist  stigma  of  the  same  flowers  or  of  other  flowers.  If 


TOMATO  289 

the  house  is  properly  heated,  the  pollen  grains  will  germi- 
nate, and  each  produce  a  slender,  threadlike  tube  that 
will  pass  down  through  the  style  to  an  ovule,  and  each 
ovule  thus  fertilized  will  develop  into  a  seed. 

If  pollination  does  not  occur,  the  flower  withers  and 
drops  off.  When  only  a  few  pollen  grains  germinate,  the 
fruit  is  likely  to  be  small,  rough  and  lopsided.  In  other 
words,  thorough  pollination  is  essential  to  satisfactory 
crops.  Numerous  experiments  and  observations  have 
been  made  to  determine  the  effect  of  cross  pollination 
and  the  influence  of  various  degrees  of  pollination. 
Some  of  the  most  exhaustive  studies  were  made  by 
Fletcher  and  Gregg  at  the  Michigan  Experiment  Station, 
who  report  as  follows  in  Special  Bulletin  39 : 

SUMMARY  OF  EXPERIMENTS 

"1.  The  six  varieties  under  experiment  were  Ignotum,  Stirling 
Castle,  Earliana,  Best-of-All,  Lorillard  and  Frogmore.  The  blos- 
soms on  four  plants  of  each  variety  were  self-pollinated,  and  the 
blossoms  of  eight  plants  of  each  variety  were  cross-pollinated  with 
two  other  varieties.  All  set  fruit  equally  well.  The  265  fruits  pro- 
duced from  self-pollination  on  all  six  varieties  had  an  average 
weight  of  7-7.3  grams.  The  534  fruits  produced  from  cross-pollina- 
tion on  all  six  varieties  had  an  average  weight  of  79.1  grams. 

"2.  Four  plants  of  each  variety  were  used  in  an  experiment  to 
determine  the  effect  of  using  varying  amounts  of  pollen.  All  the 
flowers  on  one  plant  of  each  variety  were  emasculated  and  pollinated 
on  one  side  of  the  stigma  only.  These  invariably  produced  lop- 
sided and  small  fruits.  All  the  flowers  of  one  plant  of  each  variety 
were  pollinated  with  from  one  to  five  pollen  grains.  These  produced 
very  small,  solid  fruits,  with  an  average  weight  of  but  34  grams  and 
having  no  seeds,  or  but  one  or  two.  All  of  the  flowers  on  one 
plant  of  each  variety  were  pollinated  with  a  large  amount  of  pollen, 
spread  all  over  the  stigma.  These  produced  fruits  that  were 
smoother  and  that  averaged  12  grams  heavier  than  fruits  produced 
from  flowers  that  had  but  a  small  amount  of  pollen  applied  all  over 
the  stigma. 

CONCLUSIONS 
"1.  The   results    of  .the   investigation   indicate   that   it   is   not   of 


290  VEGETABLE  FORCING 

primary  importance  to  cross-pollinate  any  of  the  six  varieties  of 
forcing  tomatoes  used  in  these  experiments,  although  it  does  no 
harm  and  may  be  a  slight  advantage  in  some  cases. 

"2.  When  pollen  falls  upon  one  side  of  the  stigma  only,  a  one-sided 
tomato  always  results.  The  larger  the  stigma  the  greater  the  ir- 
regularity. 

"3.  The  amount  of  pollen  applied  to  the  stigma  determines,  to  a 
great  extent,  the  size  and  smoothness  of  the  tomato ;  but  after  apply- 
ing a  certain  amount  of  pollen  no  further  increase  in  size  or  weight 
results  by  applying  more.  The  small  irregular  tomatoes  grown  under 
glass  are  caused  largely  by  insufficient  pollination. 

"Similar  results,  as  regards  the  effect  of  insufficient  pollination, 
were  obtained  by  Bailey  and  Munson ;  and  the  conclusion  that  cross- 
pollination  is  not  essential  is  supported  by  Troop,  who  found  that 
Success  tomato,  when  grown  under  glass,  matured  practically  as 
many  and  as  large  tomatoes  from  self-pollination  as  from  cross- 
pollination  with  Stone  and  Combination." 

In  the  culture  of  tomatoes  at  midwinter,  it  is  believed 
that  light  yields  are  due  more  to  imperfect  pollination 
than  to  any  other  factor.  After  March  15,  when  there 
is  more  sunshine  and  temperatures  are  higher  and  ven- 
tilation freer,  the  atmospheric  conditions  are  more  favor- 
able for  a  full  setting  of  fruit. 

When  tomatoes  are  grown  out  of  doors,  there  is  no 
need  of  artificial  pollination.  In  the  greenhouse,  condi- 
tions are  quite  different  and  some  assistance  is  needed, 
especially  during  the  winter  months. 

The  best  results  in  hand  pollination  are  obtained  if  the 
work  is  done  when  the  sun  is  shining  and  the  air  of  the 
house  is  as  dry  as  possible.  Ordinarily,  from  10  to  12 
o'clock  in  the  morning  is  the  best  time  of  the  day.  Care 
should  be  exercised  that  the  plants  be  as  dry  as  possible 
at  this  time  and  also  that  the  humidity  be  low. 

Pollen  is  not  discharged  from  the  anthers,  nor  are  the 
stigmas  receptive  to  pollination  until  the  flowers  are  well 
developed,  a  condition  shown  by  the  fully  expanded 
petals. 

Various  methods  of  artificial  pollination  are  employed 


TOMATO  291 

and  are  effective  under  different  conditions.  The  most 
thorough  method  is  to  collect  the  pollen  grains  in  a 
shallow  receptacle  like  a  glass  or  a  small  ladle  and  then 
to  pass  from  flower  to  flower.  The  receptacle,  attached 
to  a  slender  handle  about  15  to  18  inches  long,  is  held 
under  the  flower,  which  is  tapped  or  jarred  with  a  spatula 
or  a  small  stick.  If  the  flowers  are  sufficiently  developed 
to  be  discharging  pollen,  a  visible  quantity  of  the  grains 
will  soon  be  collected,  and  then  the  operator  proceeds 
from  flower  to  flower,  holding  the  ladle  so  that  the 
stigmas  of  each  pistil  will  come  into  contact  with  the 
pollen  grains  as  each  flower  is  tapped.  The  quantity  of 
pollen  gradually  increases  as  the  work  proceeds.  This 
seems  like  a  very  slow,  tedious  task,  but  the  increased 
yields  may  more  than  pay  for  the  expense  involved. 
This  method  is  especially  desirable,  because  of  its  thor- 
oughness, for  use  during  the  winter  months. 

Some  growers  pass  from  flower  to  flower  with  a 
camel's  hair  brush.  Under  favorable  conditions  sufficient 
pollen  will  adhere  to  the  brush  to  make  the  method  fairly 
effective,  but  it  is  not  as  thorough  as  when  a  shallow 
receptacle  is  used. 

The  commonest  plan  in  pollinating  for  the  spring  crop 
is  to  jar  the  plants.  This  is  generally  done  with  a  padded 
stick  or  perhaps  a  piece  of  rubber  hose  placed  over  a 
stick  of  convenient  length.  The  stem  of  the  plant  should 
be  tapped  near  the  flowers  which  it  is  desired  to  pollen- 
ize.  Growers  who  use  a  rigid  wire  trellis  simply  jar  it 
at  intervals  of  several  feet.  This  plan  results  in  heavy 
settings  of  fruit  when  English  varieties  are  used,  such  as 
Comet  and  Peerless.  When  the  jarring  method  is  used 
the  plants  or  trellises  should  have  daily  attention.  Every 
other  day  is  considered  sufficient  when  each  flower  is 
separately  pollinated. 

Inasmuch  as  the  earliest  fruits  command  the  highest 
prices,  and  weather  conditions  are  usually  most  unfavor- 


292  VEGETABLE  FORCING 

able  for  pollination,  some  growers  hand  pollinate  each 
flower  on  the  first  cluster  or  two  and  then  jar  the  plants 
to  distribute  the  pollen  for  the  balance  of  the  crop. 
Varieties  differ  greatly  in  their  ability  to  set  a  good  crop 
of  fruit.  English  varieties  are  especially  profuse  in  the 
discharge  of  pollen. 

Insects. — The  white  fly  is  the  most  serious  enemy  of 
greenhouse  tomatoes.  For  description,  life  history  and 
methods  of  control  see  page  120.  The  nematode  is  also  a 
serious  pest.  (See  page  116.)  Red  spiders  (page  123)  and 
the  green  aphis  (page  119)  sometimes  make  it  necessary 
to  use  control  measures. 

Diseases. — General  questions  relating  to  the  control  of 
diseases  affecting  greenhouse  crops  are  discussed  in 
Chapters  VI  and  VIII.  The  tomato  has  its  full  quota  of 
diseases.  Most  of  them  are  much  more  serious  during 
the  late  fall  and  winter  months.  This  is  one  of  the  chief 
reasons  for  growing  them  most  largely  as  a  spring  crop. 
In  the  control  of  the  various  diseases  affecting  green- 
house tomatoes,  the  greatest  reliance  should  be  placed  on 
preventive  measures,  such  as  soil  sterilization,  careful 
watering,  proper  ventilation  and  skillful  fertilization. 
All  diseased  parts  should  be  promptly  removed  if 
possible  and  destroyed. 

Leaf  mold  (Cladosporium  fulvum,  Cooke)  is  considered 
the  most  serious  disease  of  greenhouse  tomatoes.  It  is 
likely  to  cause  particular  trouble  during  cool,  cloudy 
weather.  It  appears  first  on  the  lower  leaves  as  irregular 
yellow  areas  on  the  upper  surface,  while  on  the  under 
side  of  these  areas  are  found  the  olivaceous  growth  of  the 
fungus.  Leaves  which  are  badly  infected  turn  yellow 
and  then  wilt  and  die,  so  that  the  entire  plant  may  be 
defoliated  by  the  spread  of  the  disease.  If  the  infection 
appears  soon  after  the  plants  are  set  in  the  beds,  it  is 
extremely  difficult  to  prevent  the  loss  of  the  entire  crop. 
If  the  plants  are  not  attacked  until  the  fruit  is  set  and 


TOMATO 


293 


well  developed  the  loss  may  be  very  slight.  Early  and 
general  infection  invariably  seriously  interferes  with 
nutrition,  and  results  in  a  light  crop  of  small  fruits  in- 
ferior in  quality.  The  most  thorough,  early  and  repeated 
spraying  of  the  upper  and  under  surfaces  of  the  leaves 
with  bordeaux  mixture  is  regarded  as  fairly  effective  in 
preventing  serious  ravages  of  the  mold.  It  is  exceed- 
ingly important  to  avoid  working  among  the  plants  when 
they  are  wet,  in  order  to  prevent  the  spread  of  the  fungus. 
If  the  disease  becomes  well  established,  no  kind  or 
amount  of  spraying  will  prove  effective. 


Fig.  93. — Blossom  end  rot  of  tomato. 

Blossom-end  rot  is  familiar  to  all  growers  of  green- 
house tomatoes.  The  characteristic  appearance  of  the 
affected  fruit  is  shown  in  Fig.  93.  The  Ohio  and  other 
experiment  stations  have  studied  the  causes  of  point  rot 
and  the  means  of  preventing  it,  and  there  seems  to  be 


294  VEGETABLE  FORCING 

almost  a  consensus  of  opinion  that  the  trouble  will  not 
appear  to  any  considerable  extent  if  the  beds  contain  a 
constant  and  abundant  supply  of  moisture.  In  this  con- 
nection, Bulletin  214  of  the  Ohio  Station  contains  the 
following  statement:  "It  was  stated  in  Bulletin  73  that 
this  trouble  was  observed  to  be  most  destructive  in  cases 
of  scant  water  supply  in  the  soil.  This  observation  was 
again  confirmed  by  the  horticultural  department  of  the 
station  during  the  season  of  1899.  The  trouble  was 
checked  by  abundant  and  careful  watering,  even  when  it 
had  been  very  bad,  and  was  again  produced  by  with- 
holding water  and  allowing  the  plants  to  dry  out.  The 
cause  appears  to  be  largely  due  to  conditions  of  drouth, 
and  while  other  causes  than  the  one  just  stated,  notably 
a  certain  bacterium,  do  join  to  produce  point  rot,  none 
other  appears  so  under  control  as  water  conditions.  The 
remedy  lies,  of  course,  in  the  avoidance  of  drouth  from 
which  the  rot  may  indirectly  result." 

Brooks,  who  conducted  some  studies  at  the  New 
Hampshire  station,  reached  conclusions  which  were 
different  from  the  views  of  Selby  and  other  investigators. 
He  reports  as  follows  in  the  October  (1914)  number  of 
Phytopathology: 

"1.  The  blossom-end  rot  of  the  tomato  is  not  due  primarily  to 
bacteria  or  fungi. 

"2.  Plants  are  most  susceptible  when  in  a  condition  of  great 
activity. 

"3.  Either  continued  excessive  watering  or  a  sudden  check  in 
the  water  supply  may  produce  the  disease. 

"4.  With  liberally  watered  greenhouse  plants  potassium  chloride 
increases  the  disease,  and  lime  and  sodium  nitrate  decrease  it.  These 
facts  have  not  been  found  to  hold  true  under  field  conditions. 

"5.  Ammonium  sulphate,  dried  blood  and  cottonseed  meal  have 
increased  the  disease  more  than  sodium  nitrate  containing  an  equiva- 
lent amount  of  nitrogen. 

"6.  Heavy  applications  of  stable  manure  have  increased  the  dis- 
ease out  of  proportion  to  the  increase  in  vigor  of  the  plants. 


TOMATO 


295 


"7.  When  well  supplied  with  water  plants  on  a  sandy  loam  have 
developed  less  disease  than  those  on  a  clay  loam. 

"8.  Raising  the  soil  temperature  of  greenhouse  plants  has  in- 
creased the  disease. 

"9.  The  writer  is  of  the  opinion  that  the  increase  in  the  disease 
from  heavy  watering  is  due  to  the  development  of  harmful  humic 
and  ammonium  compounds  and  an  accompanying  decrease  in  ni- 
trates. 

"10.  Susceptible  tissue  has  more  starch  and  more  oil  than  normal 
tissue  and  its  cell  sap  has  a  higher  osmotic  value. 

"11.  The  protoplasm  in  the  cells  from  the  fruit  of  the  heavily 
watered  plants  is  more  granular  and  contains  more  oil  than  that 
of  the  lightly  watered  ones." 


Fig.  94. — A  convenient  picking  basket. 

Leaf  spot  or  leaf  blight  (Septoria  Lycopersici  Speg.) 

sometimes  attacks  greenhouse  tomatoes.  It  appears  on 
the  leaves  as  numerous  oval  or  circular  spots.  The  in- 
terior of  the  spots  is  light  in  color  while  the  margins  are 
dark.  Bordeaux  mixture  is  recommended  for  the  control 
of  this  disease. 

Alternavia  solani  (E  and  M)  J  and  G,  is  another  form 
of  blight  which  is  sometimes  encountered  in  the  culture 


296  VEGETABLE  FORCING 

of  greenhouse  tomatoes.     Bordeaux  mixture  is  appar- 
ently the  best  spray  material  to  combat  this  disease. 

Various  other  diseases,  such  as  Fusarium  wilt,  anthrac- 
nose,  mosaic  or  calico  leaf  and  bacterial  blight,  are  often 
found  on  greenhouse  tomatoes,  but  the  most  important 
diseases  are  the  Leaf  Mold  and  Blossom-End  Rot. 


Fig.  95. — Each  paper  box   holds  six  pounds  of  tomatoes,    and   eight  boxes  may  be 
packed  in  a  standard  bushel  box,  such  as  is  used  in  the  Boston  district. 

Marketing. — Greenhouse  tomatoes  should  not  be  har- 
vested until  they  are  well  colored,  because  quality  is  in- 
variably sacrificed  if  they  are  picked  too  green.  If  to  be 
sold  on  a  local  market,  there  is  no  necessity  for  picking 
them  before  they  are  fully  ripe.  It  is  desirable  to 
examine  the  plants  at  least  three  times  a  week  in  order 
to  remove  all  specimens  at  the  proper  degree  of  ripeness. 
The  fruits  should  be  handled  with  great  care,  to  avoid 
bruising,  and  it  is  customary  to  pick  them  with  the  calyx 
attached.  Early  in  the  forenoon  is  the  preferable  time 
for  gathering  the  fruits  because  they  are  then  cooler  and 
more  solid  than  at  midday  when  the  sun  may  be  shining 
and  the  houses  are  very  warm. 

The  fruits  are  wiped,  if  necessary,  with  a  damp  cloth 
and  then  graded.  Rigid  grading  is  absolutely  necessary 
if  a  reputation  for  first-class  fruit  is  desired.  No.  1  or 
fancy  grades  should  be  free  from  very  small,  ill-shaped, 
cracked,  bruised,  spotted  or  otherwise  defective  speci- 


TOMATO 


297 


mens.     Ordinarily  there  is  no  advantage  in  having  more 
than  two  grades. 


Fig.  96. — Tomatoes   are  sometimes   wrapped   and   packed    in    the   manner  shown   in 
this   illustration. 

A  great  many  different  kinds  of  packages  (Figs.  95,  96, 
97  and  98)  are  used  for  the  handling  of  forced  tomatoes. 
They  vary  in  capacity  from  4  to  25  pounds.  Baskets 
similar  in  shape  to  those  in  which  grapes  are  packed  so 
extensively  are  most  largely  employed.  The  quantity 
commonly  packed  in  a  basket  is  10  pounds,  though  1.5  and 
20-pound  sizes  are  not  unusual,  especially  for^he  spring 
crop,  when  prices  are  relatively  low.  Some  growers  use 
paper  cartons  of  various  descriptions.  New  England 
growers  often  pack  eight  paper  boxes,  each  holding  six 
pounds  of  fruit,  in  their  standard  bushel  box,  which  may 
then  be  crated  for  shipment.  The  weighing  of  the  toma- 
toes should  be  accurate,  so  that  there  can  be  no  complaint 
on  that  account. 

Winter  tomatoes  are  always  wrapped  in  paper  unless 
they  are  sold  on  a  local  market.  To  insure  safe  trans- 
portation a  common  practice  is  to  place  a  layer  of  ex- 
celsior in  the  bottom  of  the  basket  and  also  between 
layers  of  the  fruit  to  prevent  bruising.  It  is  an  advantage 


298  VEGETABLE  FORCING 

to  place  a  layer  or  two  of  paper  on  top  of  the  excelsior, 
before  packing  the  tomatoes.  Lids  may  be  used  or  the 
baskets  may  be  wrapped  in  paper  and  securely  tied 
preparatory  to  shipment. 

Yields  and  returns. — Yields  of  greenhouse  tomatoes 
are  extremely  variable.  Late  fall  and  winter  crops  are 
the  lightest  and  spring  crops  the  heaviest.  Two  pounds 
per  square  foot  is  considered  a  satisfactory  yield,  though 
this  amount  is  often  exceeded.  The  following  yields  have 
been  reported  by  prominent  growers  in  the  various  sec- 
tions indicated:  An  Irondequoit  (N.  Y.)  grower 
averaged  12  pounds  to  the  plant  one  season,  with  Peer- 
less as  a  spring  crop  in  a  30  by  180-foot  house ;  seven  rows 
in  the  house,  120  plants  in  each  row,  or  840  in  the  house, 
about  10  clusters  on  each  plant,  and  an  average  of  six 
tomatoes  per  cluster.  This  grower  usually  averages  about 
10  pounds  to  the  plant.  A  Cleveland  grower  harvested 


Fig.  97. — A  unique  way  of  packing  a  number  of  small  boxes  of  tomatoes. 

4,000  pounds  of  Globe  and  Magnus  from  400  plants,  18 
to  25  tomatoes  to  the  plant.  A  New  Castle  (Pa.) 
grower  averages  about  10  pounds  of  Globe  to  the 
plant.  A  Boston  grower  picked  13,360  pounds  of  fruit 
from  1,670  plants  set  15  inches  by  3  feet.  Eight  pounds 


TOMATO 


299 


per  plant  were  picked  from  2,200  plants  of  Grand  Rapids 
Forcing  by  a  western  grower.  Five  to  seven  pounds  to 
the  plant  is  a  common  yield  of  Comet,  set  20  by  20,  in 
the  Kennett  Square  (Pa.)  region. 

Prices  for  greenhouse  tomatoes  vary  from  a  few  cents 
a  pound  to  40  cents  or  even  more  sometimes.  The  winter 
crop,  of  course,  commands  the  highest  prices.  Perhaps 
•30  cents  a  pound  is  a  fair  average  for  the  winter  crop. 
The  spring  crop  generally  starts  at  about  15  cents,  some- 
times higher,  the  bulk  being  sold  at  10  to  12  cents,  and 
the  last  few  pickings  at  9  cents  or  less.  Perhaps  11  cents 
a  pound  is  a  fair  average  wholesale  price  for  the  spring 
crop  in  most  sections,  covering  a  period  of  10  years.  The 
spring  crop  ought  to  produce  over  20  cents  per  square 
foot  of  bed  area. 


Fig.   98. — The   Boston   bushel   box,   showing  the   upper  tier   of  six-pound   packages. 


CHAPTER  XVIII 
CUCUMBER 

History. — The  cucumber  has  been  grown  under  glass 
in  the  United  States  since  the  earliest  days  of  vegetable 
forcing.  The  largest  plantations  during  the  decade  of 
1890  to  1900  were  found  in  the  Boston  district,  in  which 
W.  W.  Rawson  was  the  best-known  grower.  At  first 
the  long  English  type  was  cultivated,  but  American  con- 
sumers have  had  a  preference  for  the  shorter  cucumbers 
of  the  White  Spine  type,  and  the  popularity  of  this  class 
has  been  largely  responsible  for  the  development  of  the 
cucumber-forcing  industry  in  other  parts  of  the  country, 
especially  in  the  Central  West. 

Importance. — It  is  impossible  to  give  a  very  definite 
idea  of  the  importance  of  the  cucumber  as  a  forcing  crop. 
In  every  vegetable-forcing  district  of  the  United  States 
it  occupies  an  important  place.  In  the  Boston  district  it 
ranks  next  to  lettuce  in  commercial  importance,  and  it  is 
believed  that  it  would  rank  second  in  importance  if  the 
entire  country  were  considered.  There  is  scarcely  a  large 
vegetable-forcing  establishment  anywhere  in  the  United 
States  that  does  not  at  some  time  or  another  grow  cu- 
cumbers for  market.  If  a  crop  requiring  high  tempera- 
tures is  to  be  grown,  either  the  cucumber  or  the  tomato 
is  generally  selected.  It  is  largely  a  matter  of  personal 
preference  or  of  the  demands  of  the  markets  to  be  sup- 
plied. See  page  1  for  more  complete  data  regarding  the 
history  of  vegetable  forcing. 

Season  of  culture. — The  cucumber  is  a  "warm"  crop, 
which  requires  even  higher  temperatures  than  the  tomato. 
Because  of  its  demands  for  heat,  this  vegetable  is  most 
extensively  grown  as  a  spring  crop.  It  generally  follows 
lettuce,  which  occupies  the  beds  until  the  arrival  of  bright, 

300 


302  VEGETABLE  FORCING 

sunny  spring- weather.  When  its  culture  is  undertaken 
through  the  dull,  cloudy  weather  of  the  fall  and  winter, 
the  plants  are  more  susceptible  to  disease  and  they  grow 
much  slower  than  during  the  spring.  The  yields,  too,  are 
much  lighter  in  the  winter  season  and  more  attention 
must  be  given  to  pollination  than  in  the  spring. 

In  fact  the  greatest  precautions  are  necessary  in  the 
production  of  late  fall  and  winter  cucumbers,  and  only 
experienced  growers  should  undertake  their  culture  under 
such  unfavorable  conditions.  Though  the  price  for  winter 
cucumbers  may  be  four  or  five  times  that  of  the  spring 
crop,  the  extra  labor  and  the  additional  coal  required 
generally  make  it  difficult  to  realize  a  profit,  and  for  this 
reason  most  greenhouse  men  prefer  to  grow  lettuce  until 
spring  or  late  in  the  winter  and  then  start  cucumbers  or 
tomatoes. 

Ground  beds  vs.  raised  benches. — As  stated  on 
page  322  there  is  no  question  about  the  value  of  bottom 
heat,  but  this  fact  does  not  indicate  that  raised  benches 
are  preferable  to  ground  beds  for  the  forcing  of  the  cu- 
cumber as  a  spring  crop. 

Experiments  conducted  by  Waid  at  the  Ohio  Experi- 
ment Station  show  that  raised  benches  produced  the  larg- 
est amount  of  early  fruit,  but  ground  beds  the  largest  total 
yield.  The  results  were  as  follows :  Plants  trained  up- 
right on  228  square  feet  of  raised  bench  produced  655 
firsts  and  87  seconds  previous  to  July  4.  Plants  trained 
upright  on  228  square  feet  of  ground  bed  produced  586 
firsts  and  67  seconds  previous  to  July  4.  The  total  yield 
of  firsts  and  seconds  from  the  raised  benches  was  748  and 
144,  respectively,  and  from  the  ground  bed  824  firsts  and 
168  seconds.  While  arguments  can  be  advanced  in  favor 
of  growing  cucumbers  on  raised  benches,  practically  all 
growers  prefer  ground  beds.  The  question  of  the  in- 
fluence of  bottom  heat  is  discussed  on  page  322. 

Varieties.— There  are  two  distinct  types  of  cucumbers, 


CUCUMBER 


303 


commonly  known  as 
the  English  (Fig.  99) 
and  the  American  (Fig. 
100).  The  English  va- 
rieties are  seldom 
grown  out  of  doors. 
While  they  possess 
special  merit  in  some 
respects  for  forcing, 
they  have  not  met  with 
general  favor  in  this 
country.  The  quality 
of  the  fruit  does  not 
seem  to  appeal  to  our 
consumers.  The  plants 
are  thrifty  in  growth; 
they  develop  thick 
stems  and  large  leaves 
and  are  exceedingly 
prolific.  The  fruits  vary 
in  length  from  a  foot  to 
2  feet  or  more,  and  in- 
dividual specimens  have  been  grown  which  weighed  over 
10  pounds,  though  this  is  more  than  double  the  size  of 
normal  English  cucumbers.  The  green,  cylindrical  fruits 
contain  few  seeds.  The  American  type,  best  represented 
by  White  Spine,  is  extensively  grown  in  nearly  all  of  our 
vegetable-forcing  establishments.  The  plants  are  vigor- 
ous in  growth,  though  not  equal  in  this  respect  to  those 
of  the  English  class.  The  length  of  typical  fruits  is  usu- 
ally about  three  times  their  thickness,  but  the  fruits  of 
the  various  strains  show  marked  variation  in  this  par- 
ticular. 

English  varieties. — The  Telegraph,  shown  by  the  long- 
est specimen  in  Fig.  101,  is  the  best  known  and  the  most 
largely  cultivated  of  the  English  varieties  in  this  country. 


Fig.    100. 
Good    specimens    of    White    Spine    cucumber. 


304 


VEGETABLE   FORCING 


Fig.  101. — The  long  cucumber  at 
the  left  is  Engl  sh  Telegraph.  The 
short  one  at  the  right  is  a  strain  of 
White  Spine.  The  middle  specimen 
is  Abundance — a  cross  between  the 
other  two  varieties. 


In  one  of  the  fruits  illustrated, 
38  seeds  were  found  and  all 
of  them  were  within  2  inches 
of  the  stem  of  the  fruit.  The 
seeds  were  slightly  larger 
than  those  of  American  cu- 
cumbers. It  was  observed 
that  the  flesh  between  the  seed 
cavity  and  the  skin  was  about 
the  same  as  in  Davis  Perfect, 
which  is  a  cross  between  an 
English  and  an  American  va- 
riety, and  the  flesh  was  not  as 
crisp  as  that  of  the  latter 
class.  Numerous  varieties  are 
described  in  English  cata- 
logues, but  Telegraph  is  the 
only  one  that  has  received 
much  attention  in  the  United 
States. 

American  varieties. — There 
are    two    general    classes    of 


American  cucumbers,  which 
may  be  designated  as  "Dark 
Spine"  and  "White  Spine. "  The  Dark  Spine  is  not  suit- 
able for  forcing  purposes;  therefore  all  pure  American 
forcing  varieties  or  strains  belong  to  the  White  Spine 
type.  Some  seedsmen  simply  use  the  term  "White  Spine" 
as  a  varietal  name,  while  others  apply  such  terms  as 
Improved  Arlington  White  Spine  (Fig.  102),  Arlington 
Extra  White  Spine,  Perfection  White  Spine,  Extra  Long 
White  Spine,  Evergreen  White  Spine,  Forcing  White 
Spine,  Improved  White  Spine  Forcing,  etc.  Other  names 
used  for  strains  of  White  Spine  are  Hill's  Forcing,  Vick- 
ery's  Forcing,  Rawson's  Hothouse  (Fig.  103),  New 
Emerald,  Stokes's  Hothouse  Perfection  and  Bay  State. 


CUCUMBER 


305 


Markets  differ  in  their  requirements,  but  most  of  them 
prefer  fruits  which  are  fairly  long  and  dark  green  in  color. 
They  should  be  uniform  in  diameter  almost  to  the  tip  of 
each  end  (see  Fig.  104),  and  the  surface  should  be  smooth 
and  regular.  When  the  fruits  are  ready  to  pick,  the  seeds 
should  be  poorly  developed.  The  flesh  should  be  crisp, 
tender  and  of  the  best  flavor. 

American  English  crosses. — As  previously  stated,  the 
texture  and  flavor  of  English  varieties  appeal  to  compara- 
tively few  American  con-  , . : , 

sumers,  though  the  long,  green, 
cylindrical  fruits  are  highly  at- 
tractive in  appearance. 

The  great  vigor  and  pro- 
lificacy of  English  varieties 
have  interested  our  green- 
house growers,  and  these  fac- 
tors, perhaps,  have  had  the 
greatest  influence  in  causing 
numerous  crosses  to  be  made 
between  the  two  types.  Most 
of  the  crosses  have  been  very 
unsatisfactory.  The  plants  have 
been  thrifty  and  prolific,  but 
the  fruits,  in  most  instances, 
have  been  too  pointed  or  taper- 
ing and  irregular  in  shape. 
However,  there  are  some  not- 
able exceptions.  One  reason  for  the  use  of  crosses  is 
the  fact  that  artificial  pollination  is  not  so  essential  as 
with  pure  American  varieties. 

Davis  Perfect  (Fig.  105),  a  cross,  is  largely  grown.  The 
plants  are  vigorous  and  productive,  both  the  stems  and 
leaves  being  very  large.  The  fruits  vary  from  about  6^/2 
inches  to  9  inches  in  length,  the  average  being  about  ll/2 
inches,  and  the  circumference  in  the  middle  about  7  inches. 


Fig.  102. 
Arlington    White    Spine    cucumber. 


306 


VEGETABLE   FORCING 


The  fruit  is  a  trifle  larger 
at  the  stem  end.  Al- 
though the  name  indi- 
cates perfection,  this  is 
not  the  case,  for  the 
fruits  are  too  much 
curved  and  there  is  too 
much  irregularity  in  size 
and  shape.  But  it  is  re- 
garded as  a  highly  de- 
sirable and  successful 
variety. 

Abundance  is  a  cross 
produced  by  Chauncey 
West  of  Irondequoit,. 
N.  Y.  Fig.  106  shows 
the  regularity  of  the 
fruits  in  size  and  shape. 
It  is  grown  exclusively 
in  the  Irondequoit  dis- 
trict and  is  gradually 
being  introduced  into 
other  sections.  This  cucumber  is  in  great  demand  in  the 
Rochester  and  Buffalo  markets.  First-class  specimens 
range  from  8  to  10  inches  in  length,  the  average 
length  being  about  9  inches  and  the  circumference  7 
inches.  The  seeds  are  more  numerous  in  the  blossom  end 
of  the  fruits  than  in  fruits  of  the  White  Spine,  but  there 
are  no  developed  seeds  within  about  5  inches  of  the  stem 
end.  The  flesh  is  tender  and  crisp  and  of  excellent  quality. 
Davis  Perfect  X  Rawson  Hothouse.  —  A  grower  in 
Western  Pennsylvania,  who  usually  plants  about  two 
acres  of  cucumbers  under  glass,  has  developed  this  cross, 
which  he  prefers  in  meeting  the  demands  of  local  markets. 
Seed. — No  vegetable  which  is  used  in  forcing  is  more 
influenced  by  the  character  of  seed  planted  than  the  cu- 
cumber. Failures  and  disappointments  are  often  traced 


Fig.   103. — Rawson  Hothouse  cucumber. 


CUCUMBER 


307 


to  the  use  of  inferior  seed. 
They  may  be  responsible 
for  low  yields,  a  large  per- 
centage of  culls  and  seri- 
ous losses  from  the  depre- 
dations of  diseases  of  va- 
rious kinds.  Cucumber 
growers  cannot  give  this 
matter  too  much  atten- 
tion. 

There  need  be  prac- 
tically no  uncertainty 
about  the  ability  of  the 
seed  to  produce,  under 
favorable  conditions,  a 
large  crop  of  the  finest 
specimens.  Small  plant- 
ings should  be  made  of 
each  lot  of  seeds  in  order 
to  determine  their  merits 
before  large  areas  are 
planted  for  commercial 
purposes.  The  adoption  of  such  a  policy  will  be  cer- 
tain to  result  in  more  uniform  success  from  year  to  year. 

Some  of  the  seedsmen  catalogue  special  forcing  strains 
or  varieties  of  cucumbers,  and  many  of  them  are  excellent. 
Most  of  the  largest  commercial  growers  prefer  to  produce 
and  save  their  own  seed.  It  is  not  unusual  for  them  to 
have  small  houses  (Fig.  107)  in  which  the  seed  crop  is 
grown.  Vigorous,  productive,  disease-resistant  plants 
are  selected,  on  which  the  fruits  are  as  uniform  as  possible 
in  color,  size  and  shape.  The  fruits  should  be  thinned  to 
five  or  six  specimens  on  each  plant.  Fig.  108  shows 
some  choice  seed  specimens  of  a  Middle  West  grower. 
One  hundred  cucumbers  of  Abundance  produced  two 
pounds  of  seed.  The  fruits  should  be  allowed  to  become 
thoroughly  ripe  before  they  are  picked  for  seed.  The 


Fig.  104. — White  Spine  cucumber.  The 
left  specimen  is  of  much  better  form  at 
stem  end. 


308 


VEGETABLE  FORCING 


seeds  are  easily  sep- 
arated from  the  pulp 
by  washing.  The 
plump,  heavy  seeds 
will  settle  to  the  bot- 
tom of  the  vessel  and 
the  pulp  and  light  seeds 
will  float,  and  may  be 
poured  off.  The  seed 
should  be  thoroughly 
dried  after  washing  and 
then  stored  in  a  dry, 
warm  room.  The  at- 
mospheric conditions 
of  any  room  in  a  resi- 
dence provided  with 
heat  will  be  satisfac- 
tory for  the  storage  of 
cucumber  seed. 

It  has  been  conclus- 
ively demonstrated  that 
cucumber  seed  should 
be  at  least  two  years  old  before  it  is  planted,  and  some 
growers  believe  that  even  older  seed  is  preferable.  The 
seeds  are  usually  viable  even  at  seven  years,  and  if 
properly  preserved  they  will  retain  their  vitality  several 
years  longer.  New  seeds  produce  the  strongest  stem 
and  leaves,  but  old  seeds  yield  the  largest  crops. 

Starting  the  plants. — The  time  required  from  seed  sow- 
ing until  marketable  fruit  develops  will  depend  on  varie- 
ties planted,  season  of  year  and  temperature  of  the  house. 
Ordinarily,  specimens  of  good  size  are  obtained  in  from 
70  to  90  days.  The  development  of  the  crop  is  slowest 
during  the  dull,  short  days  of  the  fall  and  winter,  and 
most  rapid  during  the  long,  bright  sunny  days  of  the 
spring  and  early  summer.  Seed  sown  the  first  of  Sep- 
tember should  produce  some  specimens  of  marketable 


Fig.    105. — Davis    Perfect  from  the   originator. 


CUCUMBER 


309 


size  early  in  Novem- 
ber; there  should  be 
full  pickings  at  Thanks- 
giving and  a  liberal 
supply  for  the  Christ- 
mas market. 

There  is  a  wide  va- 
riation in  the  time  of 
starting  the  plants  for 
the  spring  crop.  A  few 
growers  sow  about 
February  15.  Many 
sow  early  in  March, 
while  some  of  the  most 
successful  greenhouse 
growers  wait  until  the 
latter  part  of  March, 
thus  growing  an  extra 
crop  of  lettuce  before 
cucumbers  are  planted 
in  the  beds.  Then,  too, 
later  sowing  not  only  saves  time,  but  the  plants  are 
generally  thriftier  and  probably  more  productive  on  ac- 
count of  higher  temperatures  and  more  sunshine.  Noth- 
ing is  gained  by  very  early  sowing  unless  a  special  market 
is  to  be  supplied.  If  the  houses  are  not  adequately  heated, 
it  is  especially  important  to  defer  sowing  until  March  1 
or  possibly  March  15.  Plants  which  have  been  started 
March  1  should  be  large  enough  to  bench  early  in  April, 
and  in  full  bearing  during  the  months  of  June  and  July. 

Too  much  emphasis  cannot  be  placed  on  the  impor- 
tance of  growing  good  plants.  The  success  of  the  crop 
depends  largely  upon  setting  in  the  beds  strong,  vigor- 
ous plants  that  have  not  been  stunted,  injured  or  checked 
in  growth  at  any  time.  Such  plants  never  fully  recover, 
and  they  generally  produce  a  large  percentage  of  small, 
irregular  cucumbers  that  grade  as  seconds  or  perhaps  as 


Fig.  106. — Abundance  from  the  originator. 


310 


VEGETABLE   FORCING 


Fig.   107. — Cucumber  seed  production  house. 

culls.  The  young  plants  must  be  given  the  best  care  in 
every  respect  in  order  to  avoid  injuries  which  are  certain 
to  be  disastrous  to  the  crop.  Very  few  greenhouse  plants 
are  so  sensitive  to  ill  treatment  as  is  the  cucumber. 

The  soil  should  contain  a  liberal  proportion  of  sharp 
sand,  if  it  is  available,  and  plenty  of  decaying  vegetable 
matter.  It  should  be  sterilized  with  steam,  if  necessary, 
to  prevent  the  ravages  of  damping-off  fungi. 

Several  methods  are  employed  in  starting  the  plants. 
The  seed  may  be  sown  in  the  beds  where  the  crop  is  to 
mature,  but  this  is  not  economical  in  the  use  of  green- 
house space. 

Many  successful  growers  sow  in  pots,  which  may  vary 
in  size  from  3  to  6  inches.  Some  of  the  most  extensive 
commercial  growers  contend  that  there  is  no  advantage 
in  using  pots  that  are  larger  than  3*/2  inches.  It  is  likely 
that  4-inch  pots  are  used  for  this  purpose  more  frequently 
than  any  other  size.  Ordinarily,  several  seeds  are  sown 
in  each  pot  and  the  plants  are  thinned  to  one  or  two, 
according  to  the  preference  of  the  grower  and  the  size  of 


CUCUMBER  311 


Fig.    108. — Special    White    Spine    cucumbers    grown    for   seed. 

the  pots.  It  is  not  unusual  for  the  seed  to  be  sown  in 
2  or  2^-inch  pots,  the  plants  being  shifted  later  to  3^  or 
4-inch  pots  before  they  are  set  in  the  beds.  They  should 
not  be  entirely  rilled  with  soil ;  a  little  space  at  the  top 
will  facilitate  watering.  If  they  are  placed  on  raised 
benches,  they  should  stand  on  a  layer  of  sand,  sifted  coal 
ashes  or  other  material  to  prevent  too  rapid  drying  out. 
If  additional  precaution  is  considered  necessary,  the  pots 
may  be  plunged  in  soil  which  is  kept  moist.  It  is  an  ad- 
vantage to  shift  the  plants  once  or  twice  before  they  are 
planted  in  the  beds.  Turning  the  pots,  changing  location 
of  plants  and  allowing  more  space  between  the  pots  may 
be  an  advantage. 

The  commonest  method  is  to  sow  the  seed  in  beds  or 
probably  in  flats.  Many  growers  sow  broadcast,  so  that 
the  seeds  are  fairly  close  together.  Others  prefer  to  sow 
in  rows,  which  vary  from  1J/2  inches  to  3  inches  apart. 
Whatever  the  method,  the  seeds  need  not  be  more  than 
barely  covered  with  soil.  One  benefit  in  using  flats  is 
that  they  may  be  covered  with  glass  which  will  protect 
the  seed  from  mice,  conserve  the  moisture  in  the  seed  bed 
and  aid  in  providing  a  higher  temperature  for  germina- 
tion. In  a  week's  time  or  less  the  seedlings  will  be  up 
and  should  be  promptly  transplanted  to  pots  of  sizes 


312 


VEGETABLE   FORCING 


previously  indicated,  berry  baskets,  or  perhaps  beds. 
(Fig.  109.)  This  work  should  be  done  with  extreme  care 
in  order  to  avoid  breaking  the  tender  roots.  If  the  flats 
or  beds  are  watered  a  few  hours  before  the  seedlings  are 
pricked  out,  there  will  be  less  breakage  of  the  roots. 

Excessive  amounts  of  water  applied  to  the  young 
plants  will  cause  them  to  become  weak  and  spindling  if 
accompanied  by  high  temperatures  and,  under  such  con- 
ditions, there  will  be  very  poor  development  of  the  roots. 
Excessive  watering  and  low  temperatures  will  check  the 
growth  and  stunt  the  plants.  They  seldom  recover  or 


Fig.    109. — A  cucumber  nursery  in   the  Boston   dijtrict. 

produce  satisfactory  crops.  On  the  other  hand,  insuffi- 
cient watering  must  be  guarded  against,  for  this  also 
prevents  proper  development.  Good  judgment  must  be 
exercised  in  this  the  most  important  operation  in  the 
growing  of  good  plants. 

Young  cucumber  plants  are  easily  injured  by  low 
temperatures.  They  demand  a  night  temperature  of  at 
least  65  degrees,  and  5  degrees  higher  is  preferable. 
The  day  temperature,  with  ventilation,  may  range  from 
75  to  90  degrees.  A  fairly  moist  atmosphere  is  favorable 


314 


VEGETABLE   FORCING 


to  the  young  plants,  and  diseases  may  be  guarded  against 
to  a  considerable  extent  by  spraying  with  bordeaux  mix- 
ture. Insect  pests  should  be  controlled  by  the  employ- 
ment of  proper  measures.  See  page  337. 

Soil. — Greenhouse  cucumbers  are  grown  in  a  great 
diversity  of  soil  types.  Most  excellent  results  have  been 
obtained  in  heavy  soils,  especially  if  they  are  well  filled 
with  organic  matter.  It  is  conceded,  however,  that  the 
light,  sandy  types  are  the  best  for  the  growing  of  this 
vegetable,  whether  in  the  open  or  under  glass.  Appar- 
ently the  most  extensive  root  development  occurs  in 
sandy  soils ;  and  for  various  other  reasons,  which  were  dis- 
cussed in  Chapters  III,  V  and  VI,  it  is  desirable  to  use 
the  lighter  soils,  if  they  are  available.  Nevertheless,  any 
soil  which  will  produce  a  good  crop  of  either  leaf  or  head 
lettuce  with  proper  management  will  yield  a  satisfactory 
crop  of  cucumbers. 

Fertilizing. — The  cucumber  requires  liberal  feeding,  in 
order  to  obtain  heavy  crops  of  first-class  fruits.  Satis- 
factory yields  or  profits  are  never  realized  from  soils  that 
are  not  well  supplied  with  available  plant  food.  A  de- 
ficiency in  this  particular  is  certain  to  result  in  a  large 
percentage  of  small,  irregular  fruits.  Rapid  growth  from 
the  date  of  sowing  until  the  crop  is  harvested  is  essential 
to  success. 

All  growers  of  greenhouse  cucumbers  depend  mainly 
upon  various  kinds  of  animal  manures  as  a  source  of 
plant  food.  Horse  manure,  fresh  or  partly  decayed,  is 
most  generally  employed.  Cattle  manure  from  city 
stockyards  is  used  by  some  of  the  most  prominent 
growers.  It  is  fine  in  texture  and  easily  applied.  Pul- 
verized sheep  manure  and  poultry  droppings  are  also 
excellent  for  this  crop. 

Organic  fertilizers,  such  as  dried  blood,  tankage  and 
bone  meal,  are  valued  by  growers  who  find  it  necessary 
to  supplement  insufficient  applications  of  stable  manures. 


CUCUMBER 


315 


They  may  be  applied  in  large  amounts  without  danger  of 
injuring  the  plants.  For  example,  a  well-known  Illinois 
grower  sometimes  uses  20  pounds  of  bone  meal  for  a  row 
of  cucumbers  100  feet  long. 


Fig.    111. — Cucumbers    and    narrow  strips    for   their    support. 

Nitrate  of  soda,  employed  in  small  amounts  as  a  top- 
dressing,  may  be  an  advantage.  Acid  phosphate  and 
potash  salts  should  be  used  sparingly  and  cautiously,  for 
the  tender  roots  of  the  cucumber  are  easily  injured  by 
chemicals.  Whatever  the  kind  or  character  of  the  fer- 
tilizer employed,  applications  seem  to  be  most  effective 
rather  late  in  the  development  of  the  crop,  after  there  is 
more  or  less  exhaustion  of  the  supply  of  plant  food  in  the 
soil  when  the  crop  was  planted.  The  same  principle  is 
involved  in  the  application  of  manure  mulches,  page  315 
which  meet  the  food  requirements  of  the  plants  when 
they  are  most  in  need  of  special  nourishment. 

Soil  preparation. — The  general  directions  of  Chapters 
V  and  VI  may  be  followed  in  the  preparation  of  soils  for 
the  forcing  of  cucumbers.  One  of  the  most  important 
considerations  is  to  see  that  the  bed  is  well  supplied  with 
organic  matter.  If  stable  manure  has  been  used  in  large 
amounts  for  lettuce,  it  may  be  unnecessary  to  apply  more 
manure  immediately  before  planting  cucumbers,  es- 


316 


VEGETABLE   FORCING 


pecially  if  fresh  horse  manure  is  to  be  applied  as  a  mulch 
after  the  plants  have  grown  to  a  height  of  several  feet. 

Planting  distances. — There  are  three  distinct  systems 
of  training  cucumbers,  and  the  proper  spacing  of  the 
plants  in  the  beds  will  depend  mainly  on  the  plan  to  be 
followed. 

When  the  upright 
system  is  used  (Figs. 
110,  111  and  112), 
the  space  between 
rows  varies  with  dif- 
ferent growers  from 
2  to  4^  feet,  and  the 
distance  between 
plants  in  the  rows 
ranges  from  10 
inches  to  2  feet.  A 
prominent  Boston 
grower  plants  2  by 
4  feet  apart,  another 
16  inches  by  4  feet, 
and  a  third  grower 
12  inches  by  4  feet, 
so  that  uniform 
planting  distances 
are  not  followed  in 
any  particular  forc- 
ingdistrict.  A 
grower  at  Cleveland, 
Ohio,  plants  18  inches 
by  4  feet,  one  at  New 
Castle,  Pa.,  15  inches  by  4  feet,  another  at  Erie,  Pa.,  2 
feet  by  3  feet,  and  another  at  Toledo,  Ohio,  16  inches  by 
4  feet.  When  two  plants  are  grown  in  each  pot,  the 
tendency  is  to  allow  more  space  between  the  pairs  of 
plants,  though  the  average  distance  between  plants  may 
be  about  the  same  as  when  they  are  planted  singly.  As 


Fig.  112.  —  Single  stem  cucumber  training. 
Note  how  the  plant  has  been  twined  about  the 
string. 


CUCUMBER  317 

with  tomatoes,  the  spacing  is  more  liberal  than  formerly. 
However,  experiments  made  by  Waid  at  the  Ohio  Ex- 
periment Station  are  favorable  to  close  planting,  as  is 
shown  by  the  following  tables  : 

TABLE  No.  1 

Table  showing  yield  of  cucumbers  on  raised  bench 
Distance  Test 

Plot  Sq.  feet  Yield  to  July  4  Total  yield 

No.          occupied        Distance  apart  set        Firsts        Seconds  Firsts      Seconds 

No.  No.  No.  No. 

1  114  Two  by  two  feet  365  50  439  83 

2  114  Rows  two  feet 

Plants  1  ft.  in  rows          342  54  395  93 

3  114  Rows  four  feet 

Plants  1  ft.  in  rows         313  33  353  51 


TABLE  No.  2 

Table   showing  yield  of   cucumbers  on  ground  bed 
Distance  Test 


Plot 
No. 

1 
2 

Sq.  feet 
occupied 

114 
114 

Distance  apart  set 

Rows  two  feet 
Plants  1  ft.  in  row 
Rows  four  feet 
Plants  1  ft.  in  rows 

Yield  to  July  4 
Firsts        Seconds 
No.             No. 

329               37 
257               30 

Total 
Firsts 
No. 

467 
357 

yield 
Seconds 
No. 

88 
80 

Waid,  in  the  Market  Growers'  Journal,  draws  the  fol- 
lowing conclusions  from  the  experiment : 

"A  careful  study  of  the  accompanying  tables  will  show  that,  so 
far  as  this  test  is  an  indication  of  what  may  be  expected,  a  larger 
yield  per  square  foot  can  be  secured  by  spacing  the  rows  two  feet 
apart  than  four  feet  when  the  plants  are  set  one  foot  apart  in  the 
rows.  Also  that  single  plants  set  two  feet  apart  each  way  will  give 
a  higher  yield  per  square  foot  than  any  other  distance  of  planting 
tried  in  this  test.  The  thicker  plantings  not  only  gave  the  greatest 
total  yield,  but  also  gave  the  largest  amount  of  early  fruit.  A  com- 
parison between  the  tables  will  show  that  the  raised  bench  gave  the 
most  early  fruit,  but  the  ground  bed  gave  the  largest  total  yield." 

When  the  A-form  system  of  training  (Fig.  113)  is 
followed,  the  plants  are  set  from  10  inches  to  18  inches 
apart  in  the  row,  12  inches  to  14  inches  being  the  most 
common  distances.  The  distance  between  the  rows 


318  VEGETABLE   FORCING 

under  the  trellis  varies  from  8  to  15  feet,  and  it  is  prob- 
able that  nothing  is  gained  by  allowing  more  than  9  or  10 
feet.  It  is  unnecessary  to  allow  more  than  a  narrow  walk 
between  the  rows  outside  of  the  trellises,  though  this  will 
depend  largely  on  the  type  of  house  construction  and  the 
width  and  arrangement  of  the  beds. 

The  English  class  of  cucumbers,  and  the  crosses  be- 
tween the  English  and  American  types,  are  often  trained 
upright  with  the  trellis  overhead,  as  illustrated  in  Figs. 
114  and  115,  which  show  the  Abundance  growing  in  a 
house  at  Irondequoit,  N.  Y.  The  plants  in  this  house  are 

4  by  5  feet  apart.    Other  plantings  have  done  well  at  3  by 

5  feet  and  4  by  4  feet  apart. 

Planting. — The  time  of  planting  in  the  beds  will  de- 
pend on  the  age  and  size  of  the  plants  and  whether  space 
is  available.  Poor  markets  or  unfavorable  conditions  of 
the  weather  make  it  impossible  sometimes  to  harvest  the 
lettuce  or  other  crops  that  precede  the  cucumbers  as  early 
as  had  been  anticipated,  when  it  may  be  necessary  to  hold 
the  cucumbers  longer  than  is  good  for  the  plants.  The 
roots  should  not  become  pot-bound,  nor  should  the  plants 
become  so  large  before  they  are  transplanted  that  it  is 
difficult  to  handle  them  without  injuring  the  stems  or 
leaves.  It  is  best  to  set  them  in  the  beds  before  they  are 
a  foot  high.  The  plants  are  generally  placed  in  the  beds 
before  April  1,  though  it  is  not  uncommon  for  planting 
to  continue  until  May  1. 

Great  care  should  be  exercised,  in  transplanting,  not  to 
break  the  balls  of  earth.  The  soil  should  be  pressed 
closely  and  firmly  about  the  roots,  and  the  beds  watered 
as  soon  as  possible. 

Watering. — The  moisture  conditions  of  both  the  soil 
and  the  atmosphere  of  the  house  demand  the  closest 
attention  for  the  forcing  of  cucumbers.  The  large,  succu- 
lent leaves,  stems  and  fruits  require  a  large  amount  of 
water,  and  any  marked  deficiency  in  humidity  or  soil 


320  VEGETABLE  FORCING 

moisture  may  cause  the  wilting  of  the  leaves  or  of  the 
entire  plant,  with  consequent  reductions  in  the  total  yield 
as  well  as  in  the  size  and  quality  of  the  cucumbers. 

The  plants  are  benefited  by  syringing  with  water,  es- 
pecially during  hot,  sunny  weather.  This  operation  may 
be  effected  very  quickly  by  producing  a  mist-like  spray 
with  the  overhead  system  of  irrigation.  If  there  are 
reasons  for  not  wetting  the  plants,  the  humidity  may  be 
increased  by  sprinkling  the  walks.  A  moist  atmosphere 
is  unquestionably  of  great  importance  in  the  forcing  of 
this  vegetable. 

As  previously  stated,  the  beds  should  be  watered  as 
soon  as  possible  after  the  plants  are  set  out.  This  will 
cause  the  soil  to  settle  about  the  balls  of  earth  and  roots 
from  the  pots,  and  thus  help  to  exclude  the  air  and  to 
establish  close  relations  between  the  moisture  of  the  soil 
and  the  roots  of  the  plants. 

Unless  the  spring  season  is  well  advanced  when  the 
plants  are  set,  large  amounts  of  water  will  not  be  needed 
until  they  are  4  or  5  feet  high,  but  from  that  time  on  pro- 
jfuse^applications  will  be  required  to  meet  their  needs. 
Dumping  the  months  of  June  and  July  it  is  practically  im- 
jfolsible  to  apply  too  much  water.  The  overhead  system 
of  watering  is  extensively  employed  in  the  growing  of 
greenhouse  cucumbers. 

Cultivation. — It  is  desirable  to  cultivate  the  beds  while 
the  plants  are  small,  but  tillage  after  the  soil  is  well  filled 
with  roots  (and  many  of  them  are  surface  feeders) 
should  not  be  advocated.  Any  damage  to  the  roots,  even 
by  shallow  tillage,  is  certain  to  impair  the  crop  of 
cucumbers. 

Mulching. — The  advantages  of  mulching  in  the  forcing 
of  tomatoes  were  fully  discussed  on  page  286.  It  is 
possible  that  the  practice  is  not  quite  so  general  in  the 
culture  of  cucumbers  under  glass,  though  a  large  per- 
centage of  the  growers  use  mulches  of  some  kind.  As  a 


CUCUMBER  321 

rule  fresh  horse  manure  is  employed,  and  a  layer  about 
3  inches  thick  is  placed  on  the  beds  after  the  plants  have 
attained  a  height  of  several  feet.  The  conservation  of 
soil  moisture  and  special  nourishment  of  the  plants  are 
especially  important  when  fruit  formation  and  develop- 
ment are  most  active.  As  pointed  out  in  the  previous 
paragraph,  many  of  the  cucumber  roots  feed  near  the 
surface  of  the  ground  where  they  are  easily  injured  by 
cultivation,  and  this  is  an  additional  reason  for  reducing 
the  escape  of  soil  moisture  by  means  of  mulches  rather 
than  by  tillage.  Very  fine  crops,  however,  are  often 
grown  without  mulching,  so  that  this  operation  cannot 
be  regarded  as  absolutely  essential  to  success. 

Temperature. — The  cucumber  requires  even  more  heat 
than  the  tomato,  as  explained  on  page  285,  and  it  is  ex- 
tremely sensitive  to  sudden  and  repeated  changes  in 
temperature.  Abnormally  low  temperatures,  after  the 
plants  are  set  in  the  beds,  will  stunt  or  check  the  growth 
and  render  the  plants  more  susceptible  to  the  ravages  of 
diseases. 

There  is  a  considerable  difference  of  opinion  concern- 
ing the  proper  night  temperature,  but  most  growers  agree 
that  it  should  not  be  lower  than  65  degrees  or  higher  than 
70  degrees.  Some  growers  who  plant  cucumbers  for  the 
spring  crop  in  beds  of  lettuce,  compromise  in  the  heat  re- 
quirements of  the  two  crops  by  maintaining  a  night 
temperature  of  about  60  degrees,  which  is  not  ideal  for 
either  vegetable. 

On  dull,  cloudy  days  the  temperature  should  be  only  a 
few  degrees  higher  than  at  night,  otherwise  the  plant 
tissues  will  become  succulent  and  tender  and  subject  to 
disease,  and  the  plants  will  be  almost  certain  to  wilt 
when  bright  sunshine  causes  a  sudden  and  pronounced 
rise  in  the  temperature,  which  cannot  be  fully  controlled 
by  means  of  ventilation.  Ordinarily,  the  day  tempera- 


322  VEGETABLE  FORCING 

ture  with  sunshine  should  be  from  80  to  85  degrees,  or 
15  degrees  higher  than  the  night  temperature. 

The  temperature  of  the  soil  is  a  subject  of  interest 
among  greenhouse  growers  of  cucumbers.  This  topic 
was  alluded  to  on  page  302,  in  the  discussion  of  ground 
beds  vs.  raised  benches.  It  will  be  recalled  that  cu- 
cumbers are  sometimes  forced  on  raised  benches.  In 
New  England,  hot  horse  manure  is  sometimes  placed  in 
trenches  in  the  greenhouse  previous  to  setting  potted 
plants,  where  it  has  much  the  same  effect  as  when  used  in 
hotbeds. 

The  higher  soil  temperature  thus  secured  is  regarded 
as  a  decided  advantage  by  some  growers,  especially  for 
the  winter  crop,  and  the  additional  fertility  must  also 
have  an  influence  on  the  growth  of  the  plants.  The  in- 
creased expense,  however,  involved  in  the  employment  of 
this  method  should  be  carefully  considered  before  one 
decides  to  follow  it. 

Moore  of  the  Wisconsin  Experiment  Station  conducted 
experiments  for  three  seasons  to  determine  the  influence 
of  bottom  heat.  Greenhouse  benches,  with  various  de- 
grees of  bottom  heat,  were  employed.  The  results  of 
these  studies  are  summarized  as  follows  in  the  24th 
Annual  Report  of  the  Wisconsin  station : 

"1.  That  a  soil  temperature  of  approximately  74  degrees  gives 
greater  fruitfulness  during  the  same  length  of  time  than  tempera- 
tures ranging  either  much  higher  or  much  lower. 

"2.  That  earliness  of  production  is  increased  very  little,  if  any, 
by  the  increase  in  soil  temperature. 

"3.  That  flower  production  is  influenced  only  slightly,  if  any, 
by  various  degrees  of  soil  temperature.  Sunshine,  atmospheric 
temperature,  and  individuality  of  plants  are  the  important  .factors 
in  this  respect. 

"4.  That  higher  soil  temperature  shortens  the  fruiting  period 
of  the  plants. 

"5.  That  the  advantages  gained  by  higher  soil  temperature  would 
not  warrant  the  additional  cost  entailed  in  increasing  it  above  that 


324  VEGETABLE  FORCING 

which  would  usually  exist  under  ordinary  forcing  conditions  em- 
ployed in  growing  this  crop. 

"6.  That  plants  possess  an  individuality  which  has  more  to  do 
with  their  behavior  than  the  different  treatments  which  would  com- 
monly be  given  in  greenhouse  operations.  That  this  individuality 
shows  itself  in  the  form  of  plant,  relative  number  of  flowers  and 
fruit  produced,  and  rapidity  of  germination  and  growth.  That 
better  results  can  be  obtained  by  using  seed  from  the  best .  in- 
dividuals than  by  attempting  to  influence  production  by  increased 
soil  temperature." 

Shading. — Shading  is  not  considered  necessary  by  all 
growers  of  the  spring  and  early  summer  crop.  Some  of 
the  most  successful  and  extensive  growers  do  not  shade 
the  houses.  If  wilting  can  be  prevented  by  proper  ven- 
tilation, sprinkling  and  watering,  it  is  doubtful  whether 
there  is  any  special  advantage  in  shading,  except  that  the 
houses  are  more  comfortable  for  the  workmen.  Shading, 
however,  is  practiced  by  some  of  the  best  growers,  but 
applications  of  any  kind  should  not  be  made  to  the  glass 
until  the  season  is  well  advanced  and  there  is  a  real 
reason  for  reducing  the  temperature  by  this  means.  See 
page  36  for  information  on  methods. 

Ventilation  is  necessary  to  maintain  the  health  and 
vigor  of  the  plants.  Inasmuch  as  the  cucumber  is  very 
sensitive  to  drafts  and  extremes  in  temperature,  the  ut- 
most care  should  be  exercised  in  ventilating.  The  vents 
should  be  opened  only  a  trifle  in  the  morning,  when  the 
temperature  has  risen  to  almost  75  degrees,  and  later  in 
the  day  they  should  be  opened  sufficiently  to  hold  the 
temperature  if  possible  at  about  85  degrees.  In  the  sum- 
mer time  the  temperature  often  exceeds  85  degrees,  but 
injuries  seldom  result  if  moisture  conditions  of  the  house 
and  soil  are  properly  controlled. 

Training  and  pruning. — The  systems  of  pruning  and 
training  the  cucumber  are  not  so  distinct  and  well  defined 
as  are  those  used  with  the  tomato.  Growers  in  various 
parts  of  the  country  differ  greatly  in  their  ideas  of  train- 
ing and  pruning.  Formerly,  there  was  a  disposition  to 


CUCUMBER  325 

do  as  little  pruning  as  possible,  and  that  of  a  haphazard 
nature.  The  English  growers  have  exercised  great  care 
in  this  operation  and,  in  recent  years,  American  growers 
have  more  fully  realized  the  advantages  of  systematic 
training  and  pruning.  The  agricultural  experiment  sta- 
tions as  well  as  many  commercial  growers  have  demon- 
strated the  value  of  following  a  fairly  well-defined  plan. 
Unless  the  vine  growth  is  limited  by  pruning,  there  is 
certain  to  be  a  large  percentage  of  culls,  and  unless  the 
plants  are  properly  trimmed,  there  will  be  too  much  shad- 
ing and  too  little  circulation  of  air. 

The  labor  item  in  keeping  the  plants  well  pruned  is 
considerable,  but  if  a  promising  market  is  expected,  the 
expense  of  such  labor  is  more  than  justifiable.  Whatever 
the  pfan,  the  work  should  always  be  done  with  care  and 
promptness.  When  the  season  is  well  advanced  and  the 
vines  are  becoming  exhausted,  and  prices  are  materially 
lower,  due  to  the  outdoor  crop,  perhaps,  too  much  time 
should  not  be  spent  in  pruning.  A  leader  here  and  there 
may  be  removed  without  much  expenditure  of  time,  and 
the  results  may  be  highly  beneficial. 

Four  fairly  distinct  systems  of  training  are  used  by 
American  growers,  namely,  the  fan  or  English  system, 
the  arbor  system,  the  A  form  and  the  upright. 

The  fan  system  does  not  have  many  advocates  in  this 
country.  It  consists  in  growing  a  single  stem  to  the 
height  of  about  18  inches,  when  the  top  is  nipped,  which 
induces  the  formation  of  a  number  of  lateral  branches, 
four  or  five  of  the  strongest  being  selected  to  train  over 
a  wire  trellis.  In  England  the  trellis  generally  runs 
parallel  to  the  roof  of  the  house,  and  if  the  house  is  nar- 
row, it  will  extend  to  the  ridge.  The  branches  run  out 
fan-shaped  from  the  main  stem  and  then  they  proceed 
to  the  top  of  the  trellis,  where  they  are  nipped.  The 
laterals  of  these  leaders  are  cut  back  more  or  less  and  the 
cucumbers  hang  below  the  trellis.  A  certain  amount  of 


326 


VEGETABLE  FORCING 


tying  is  necessary  to  secure  the  leaders  to  the  wires  of 
the  trellis.  This  system  of  training  is  best  adapted  to 
varieties  that  are  most  vigorous  in  growth,  such  as  the 
English  type.  It  is  necessary  to  set  the  plants  4  or  5  feet 
apart  in  order  to  have  sufficient  space  to  train  up  the 
branches. 

The  arbor  (or  modified  upright)  system  of  training  is 
well  illustrated  in  Figs.  114  and  115.  With  this  system 
of  training  a  single  stem  is  grown  until  it  reaches  the  wire 
arbor  at  a  height  of  about  6  feet  from  the  ground.  The 
laterals  of  this  stem  are  pinched  just  beyond  the  first 
female  blossom,  but,  as  a  rule,  not  more  than  five  or  six 
cucumbers  are  allowed  to  develop  below  the  trellis.  After 
the  main  stem  is  pinched  back,  branches  grow  out  in 
every  direction  and  soon  cover  the  trellis,  forming  an 
arbor  with  the  cucumbers  suspended  below.  A  certain 
amount  of  pruning  is  then  necessary  to  prevent  too  much 
vining.  This  system  is  especially  well  adapted  to  the 
Abundance  or  other  American-English  crosses.  The 
main  stem  is  supported  by  a  string  and  the  trellis  is  made 
of  No.  16  wires,  6  inches  apart,  running  through  light 
strips  placed  at  intervals  of  about  8  feet. 

The  A-form  system  is  largely  used  in  the  United  States. 
It  is  popular  in  New  England  and  also  in  western  forc- 
ing sections.  The  system  as  shown  in  Fig.  113  is  con- 
sidered highly  satisfactory  by  many  growers,  especially 
in  the  amount  of  light  and  sunshine  which  each  plant  re- 
ceives. The  trellis  may  be  made  of  wires  placed  about 
10  inches  apart,  running  through  2  by  4  scantlings,  which 
are  connected  in  the  form  of  the  letter  A  sufficiently  close 
to  give  proper  support  to  the  wires  and  plants.  Single- 
stem  plants  are  trained  over  the  trellis,  by  tying  them  as 
they  reach  each  wire,  until  they  reach  the  last  wire,  when 
the  tops  are  nipped.  All  of  the  laterals  are  also  nipped, 
usually  just  beyond  the  first  female  blossom.  Secondary 
laterals  may  be  allowed  to  develop  if  desired,  but  this  is 


328  VEGETABLE  FORCING 

not  necessary  to  get  a  good  crop  of  fruit.  The  cucumbers 
are  easily  harvested  as  they  hang  under  the  trellis. 

The  upright  form  of  training  (Figs.  110  and  112)  is 
unquestionably  the  most  popular  system  used  in  the 
United  States.  It  provides  for  a  single  stem  that  may  be 
trained  only  a  few  feet  high,  or  it  may  be  grown  to  a 
height  of  8  feet  or  more.  Ordinarily  it  is  not  more  than 
7  feet  in  height.  Each  lateral  is  generally  pinched  beyond 
the  first  node,  where  one  or  more  fruits  nearly  always 
develop,  and  cucumbers  are  also  borne  along  the  main 
stem.  Some  growers  allow  considerable  branching  over- 
head, where  the  vines  are  supported  by  wires,  and  such 
branches  produce  fruit  late  in  the  season  or  during  the 
latter  period  of  harvesting.  This  plan  is  popular  in  the 
Boston  district,  where  the  rows  run  across  the  house  in- 
stead of  lengthwise.  Wires  are  stretched  overhead  the 
full  width  of  the  house  and  fastened  with  screw  hooks  or 
perhaps  secured  to  pipes.  A  few  light  wires  which  are 
above  the  heavier  cross  wires  run  lengthwise,  thus  form- 
ing a  sort  of  trellis.  Wires  are  also  run  across  the  beds 
at  the  ground,  below  the  overhead  cross  wires,  and  they 
are  secured  to  staples  driven  in  the  wooden  side  boards 
of  the  beds.  Several-ply  jute  twine  is  stretched  for  each 
plant,  between  the  lower  and  upper  wires,  and  the  plant 
as  it  grows  is  quickly  twined  about  the  string,  no  tying 
being  necessary.  This  system  of  training  is  well  adapted 
to  the  American  type. 

Some  growers  prefer  not  to  allow  the  plants  to  branch 
at  the  top.  This  results  in  a  more  intensive  system.  For 
example,  in  one  section  of  Massachusetts,  where  the 
houses  are  comparatively  small  and  there  are  many  of 
them,  the  plants  are  set,  rather  early  in  the  fall,  on  raised 
beds  with  bottom  heat.  In  some  instances  the  plants  are 
not  permitted  to  attain  a  height  of  more  than  4  feet. 

The  soil  on  the  beds  is  about  a  foot  deep  and  the  plants 
are  liberally  fed  with  liquid  manure  to  prevent  them  from 


CUCUMBER 


329 


becoming  exhausted.  With  such  an  intensive  system,  and 
with  soil  that  is  fairly  heavy,  the  fall-set  plants  are  kept 
in  bearing  until  June  or  July.  The  closest  and  most  care- 
ful attention  is  required  to  accomplish  this,  and  the  sys- 
tem does  not  appeal  to  extensive  growers  of  greenhouse 
cucumbers. 

Fig.  Ill  represents  a  system  of  support  devised  by  a 
prominent  Toledo  grower.  A  strip  of  wood  ^  by  1  inch 
and  about  7  feet  long  is  placed  beside  each  plant.  A  thin 
block  3  inches  long  is  nailed  onto  the  lower  end  to  pre- 
vent the  strip  from  sinking  into  the  ground.  The  tops  of 
the  strips  are  secured  to  wires  running  lengthwise  of  the 
house.  Pairs  of  nails 
are  driven  through 
the  flat  way  of  the 
strip  at  intervals  of  a 
foot  apart  and  the 
nails  are  Y^.  inch 
apart.  One  nail  is 
twice  as  long  as  the 
other,  so  that  it  can 
be  bent  at  right 
angles.  The  stem  of 
the  cucumber  is 
placed  between  the 
nails,  and  when  the 
bent  nail  is  turned 
until  it  rests  upon 
the  other  nail,  the 
stem  is  held  securely 
in  place  without  any 
tying. 

Pollination.  — The 
cucumber  is  monoe- 
cious, that  is,  the  Fig.  116. — Single  stem  training  of  cucumbers. 

sexual  organs,  pistils  lo of  male  and  female  flowers  and  the 


330 


VEGETABLE   FORCING 


and  stamens, 
are  borne  in 
separate  flow- 
ers on  the  same 
plant.  Figs.  116 
and  117  show 
that  the  flowers 
are  axillary  and 
that  several 
fl  owe  r  s  or 
pickles  may  be 
produced  in  the 
axil  of  the  same 
leaf,  whether  it 
is  on  the  main 
stem  or  an  axil- 
lary branch,  as 
illustrated  in 
Fig.  116.  This 
fact  should  be 
kept  in  mind 
when  pruning, 

more  CUCUtTl- 
1  -11  1_  1  £• 

bers  will  be  left 
on  the  vines  than  will  attain  large  size.  The  female 
or  pistillate  flower  is  easily  recognized  by  the  ovary  or 
tiny  "pickle,"  as  seen  in  both  of  these  illustrations.  The 
yellow  corolla  is  somewhat  larger  than  in  the  sterile 
flowers.  The  pistil  is  compound  and  the  stigmas  are  two- 
lobed.  The  male  or  sterile  flowers  are  much  more 
numerous  than  the  fertile  flowers,  and  their  stamens  are 
more  or  less  coherent. 

When  .cucumbers  are  grown  out  of  doors,  bees  and 
other  insects  carry  the  pollen  from  the  male  to  the  female 
flowers  and  thus  fertilize  them.  In  the  greenhouse,  bees 


Fig.  117.  —  Branch  of  cucumber  showing  male  and 
female  flowers.  The  latter  may  be  recognized  by  the 
miniature  pickles. 


CUCUMBER  331 

must  be  kept,  or  the  pollen  transferred  by  hand,  in  order 
that  the  flowers  may  be  pollenized.  It  is  well  known, 
however,  that  pollination  is  not  always  necessary  in  order 
to  insure  the  'development  of  fruit;  but  this  statement 
applies  more  particularly  to  the  pure  English  varieties 
rather  than  to  American  or  American-English  crosses. 
In  this  connection,  Bailey,  in  Bulletin  31,  Cornell  station, 
makes  the  following  statement: 

"There  is  a  question,  however,  if  pollination  is  advisable  in  the 
house,  for  it  is  certain  that  the  English  cucumber  will  grow  to  per- 
fection without  seeds  and  entirely  without  the  aid  of  pollen.  I  do 
not  know  if  this  is  true  of  the  common  cucumbers,  but  we  have 
made  several  unsuccessful  efforts  to  grow  Medium  Green 
(Nichol's  Medium  Green)  in  the  house  without  pollination.  White 
Spine  sets  without  pollen,  apparently.  In  the  early  days  of  cu- 
cumber forcing  hand  pollination  was  practiced,  but  it  has  been 
abandoned  by  many  growers.  It  is  possible  that  the  forcing  cu- 
rumber  sets  more  freely  now  without  pollen  than  it  did  before  its 
characters  were  well  fixed,  or  perhaps  the  early  gardeners  per- 
formed an  unnecessary  labor.  Many  gardeners  suppose  that  pollen 
causes  the  fruit  to  grow  large  at  the  end,  and  they  therefore  aim 
to  produce  seedless  cucumbers  for  the  double  purpose  of  saving 
labor  and  of  procuring  straighter  and  more  shapely  fruits.  For 
two  winters  we  have  performed  many  experiments  upon  these  ques- 
tions, but  we  are  not  yet  able  to  make  many  definite  statements 
concerning  them.  We  have  found,  however,  that  it  pays  to  pollinate 
by  hand  if  early  fruits  are  desired.  The  early  flowers  nearly  al- 
ways fail  to  set  if  pollen  is  withheld,  but  late  flowers  upon  the  same 
plant  may  set  freely  with  no  pollen.  We  follow  the  same  method 
advised  by  Abercrombie  and  other  writers  of  last  century — pick 
off  a  staminate  flower,  strip  back  the  corolla,  and  insert  the  column 
of  anthers  into  a  pistillate  flower.  Fruits  which  have  set  without 
pollination  are  uniformly  seedless  throughout,  the  walls  of  the  ovules 
remaining  loose  and  empty.  Pollination  does  not  occur  when  the 
fruits  are  left  to  themselves  in  the  forcing  house,  especially  in  mid- 
winter, when  pollen-carrying  insects  are  not  present.  Upon  old 
plants  we  often  prevent  pollination,  for  experimental  purposes,  by 
tying  together  the  flower  tube,  or  occasionally  by  cutting  off  the 


332  VEGETABLE  FORCING 

flower  bud  altogether  from  the  ovary  or  young  cucumber,  but  this 
latter  method  is  uncertain." 

Whatever  may  be  the  practice  of  English  growers  with 
their  favorite  varieties,  American  greenhouse  men  have 
found  it  necessary  to  give  close  attention  to  the  matter  of 
pollination,  whenever  American  varieties  or  crosses  are 
employed.  Unless  the  female  flowers  are  fertilized  they 
wither  and  fall  off. 

The  pistillate  or  pollen-producing  flowers  are  open  only 
one  day;  they  close  in  the  evening  and  fall  off  a  day  or 
two  later.  The  female  flowers  may  remain  open  two  or 
three  days.  They  close  as  soon  as  fertilized  and  then  the 
petals  soon  wither  and  drop. 

The  pollen  grains  may  be  transferred  to  the  female 
flowers  by  the  use  of  a  camel's  hair  brush,  or  by  taking 
the  male  flower  and  bringing  the  anthers  into  contact 
with  the  pistils,  as  previously  explained.  Both  methods, 
however,  are  tedious  and  impracticable  and  require  too 
much  time  for  employment  in  commercial  establishments. 

American  greenhouse  growers  of  cucumbers  rely  al- 
most wholly  upon  bees  to  carry  the  pollen  from  flower  to 
flower.  Formerly,  apiaries  were  kept  near  the  green- 
houses, and  growers  depended  on  enough  bees  entering 
the  houses  through  the  ventilators  to  pollenize  the 
flowers.  But  the  plan  was  not  thorough,  and  now  hives 
of  bees  are  placed  in  the  houses  or  just  outside,  with 
panes  of  glass  removed  from  the  house  at  the  hives.  A 
great  many  bees  fly  from  flower  to  flower,  thus  convey- 
ing the  pollen,  a  plan  which  insures  a  heavy  setting  of 
fruit.  A  record  was  kept  in  one  of  the  Boston  sections  of 
the  sales  of  cucumbers  fertilized  by  61  hives  of  bees,  and 
the  average  return  for  a  colony  was  $815.  Our  American 
growers  attach  great  importance  to  the  part  which  the 
bee  takes  in  producing  large  crops,  and  the  matter 
demands  the  most  careful  consideration. 

The  number  of  bees  or  hives  required  for  a  given  area 


CUCUMBER 


333 


depends  upon  the  strength  of  the  colonies.  One  strong 
colony  with  a  prolific  queen  may  do  as  much  work  as  two 
or  three  weak  ones.  It  is  exceedingly  important  that  an 
ample  number  of  bees  be  provided,  otherwise  there  will 
be  a  poor  setting  of  fruit.  Close  observation  of  the  bees 
at  work,  as  well  as  the  setting  of  the  fruit  from  day  to 
day,  will  enable  one  to  determine  whether  all  the  flowers 
are  being  pollenized.  There  is  much  difference  of 
opinion  among  growers  concerning  the  number  of  hives 
required,  but  one  strong  colony  for  a  house  of  average 


Fig.  118. — Hive  of  bees  at  end  of  greenhouse. 

width  and  200  feet  long  should  be  adequate,  though  two 
colonies,  one  at  each  end  of  the  house,  would  be  more 
certain  of  providing  the  thorough  pollination  of  all 
flowers.  In  very  large  establishments  hives  are  usually 
placed  at  intervals  throughout  the  houses,  so  that  the 
bees  will  be  well  distributed. 

Many  growers,  even  with  small  ranges,  prefer  to  keep 


334 


VEGETABLE  FORCING 


the  hives  of  bees  inside  the  houses,  and  this  is  necessary 
if  the  bees  must  work  before  outside  weather  conditions 
are  suitable  for  their  comfort.  The  hives  are  generally 
at  the  ends  of  the  houses,  and  they  should  be  shaded  to 
keep  them  as  cool  as  possible. 

Other  growers  keep  the  bees  just  outside  the  houses, 
as  shown  in  Figs.  118  and  119.  This  plan  is  preferable 
from  the  standpoint  of  the  bees,  for  the  conditions,  except 
when  they  are  working  in  the  houses,  are  normal  and 
they  keep  in  better  health.  If  desired,  there  may  be  open- 
ings into  the  hives  on  two  sides,  so  that  the  bees  may 
enter  the  greenhouse  where  a  pane  of  glass  has  been  re- 
moved, or  they  may  work  on  plants  out  of  doors,  which 


Fig.   119. — Box  containing  several  hives  of  bees. 

has  the  effect  of  stimulating  better  health  and  greater 
activity.  This  plan  is  now  followed  by  some  of  the  most 
careful  and  successful  growers,  and  especially  by  those 
who  are  interested  in  bees  as  well  as  in  cucumbers.  Bees 
should  be  placed  in  the  houses  as  soon  as  the  plants  begin 
to  blossom.  The  earliest  fruits  are  the  most  profitable, 
and  there  should  be  no  uncertainty  about  the  flowers 
being  properly  fertilized. 

The  use  of  bees  in  cucumber  houses  is  necessarily  ex- 


CUCUMBER  335 

haustive  to  the  insects.  They  naturally  resent  confine- 
ment and  such  abnormal  conditions.  The  cucumber,  too, 
though  it  supplies  pollen  which  the  bees  gather,  produces 
practically  no-  nectar.  Unless  unusual  care  is  exercised, 
the  colonies  soon  become  very  weak  and  unfit  for  the 
performance  of  their  important  work  in  the  forcing  of 
cucumbers.  Most  of  our  commercial  growers  are  not 
apiarists,  and  they  have  no  interest  in  bees  except  as  they 
are  essential  in  the  forcing  of  cucumbers.  Such  men  do 
not  devote  more  time  to  the  bees  than  is  absolutely 
necessary.  They  often  prefer  to  buy  new  colonies  every 
year,  and  then  simply  sacrifice  them  for  the  crop  of  cu- 
cumbers. In  some  -sections,  as  around  Boston,  some 
apiarists  make  a  business  of  producing  bees  mainly  or 
perhaps  especially  for  cucumber  growers,  and  a  good 
price  is  generally  charged  for  the  colonies.  Pure  Italian 
bees  are  considered  the  best  workers,  and  they  are  also 
more  docile  and  not  so  ill-tempered  as  common  bees  and 
crosses  between  the  blacks  and  Italians. 

The  hives  of  bees  should  be  placed  in  the  houses  during 
the  night  and  the  entrances  opened  the  next  morning. 
The  bees  will  be  very  impatient  for  a  few  hours  or  per- 
haps a  day  or  two,  and  some  of  them  are  always  lost  in 
their  repeated  attempts  to  escape  by  flying  against  the 
glass.  If  the  ventilators  are  kept  closed,  or  nearly  so,  for 
a  couple  of  days,  or  until  the  bees  have  adjusted  them- 
selves to  the  new  conditions,  comparatively  few  will 
escape.  It  is  unnecessary  to  screen  the  ventilator  open- 
ings, for  a  large  percentage  of  the  bees  that  venture  out- 
side will  find  their  way  back  to  the  hives.  Placing  the 
hives  just  outside  the  houses  is  a  great  advantage  from 
this  standpoint.  An  excellent  plan  when  the  weather  is 
warm  is  to  remove  a  pane  or  two  of  glass  in  the  corners 
of  the  houses  so  that  the  bees  can  get  out  when  they 
worry  themselves  by  bumping  against  the  glass.  They 
will  find  their  way  back  through  the  ventilator  openings 


336  VEGETABLE  FORCING 

to  the  hives  if  they  are  placed  outside  the  greenhouses. 

Unless  the  colonies  are  well  supplied  with  honey,  it 
will  be  necessary  to  furnish  additional  feed,  except  when 
the  colonies  are  outside  and  there  is  satisfactory  bee 
pasturage  in  the  neighborhood.  The  feed  may  consist  of 
honey  or  sugar  syrup.  The  bee  needs  a  certain  amount 
of  water.  Some  growers  think  it  is  an  advantage  to  keep 
water  in  a  few  crocks,  with  thin  boards  floating  on  the 
surface.  By  most  growers  it  is  believed  that  the  bees  get 
all  the  water  they  need  without  any  special  provision. 
Care  should  be  exercised  not  to  spray  the  plants  when 
the  bees  are  working  for  they  are  easily  knocked  to  the 
ground  and  drowned.  Early  morning  watering  will  usu- 
ally avoid  any  trouble  of  this  kind. 

The  bee  moth  is  especially  destructive  to  greenhouse 
colonies.  The  hives  should  be  examined  at  frequent 
intervals  and  the  larvae  of  the  moth  removed  before  they 
have  done  much  injury.  Mice  are  also  destructive  to 
bees  and  the  openings  to  the  hives  should  be  so  small 
that  mice  cannot  enter. 

With  fair  treatment,  a  colony  of  bees  kept  inside  will 
last  at  least  8  weeks,  or  long  enough  to  pollenize  a  spring 
crop.  If  the  colonies  should  become  weak  and  inefficient 
at  any  time,  new  ones  should  be  promptly  substituted. 

An  additional  argument  for  placing  the  hives  outside 
the  houses  is  that  fumigation  with  tobacco  or  cyanide 
will  not  impair  the  health  of  the  bees,  as  it  certainly  will 
unless  the  hives  are  removed  at  such  times. 

Intercropping. — The  cucumber,  on  account  of  its  large 
leaves  and  vigorous  habit  of  growth,  is  not  well  adapted 
to  companion  cropping.  However,  lettuce  and  other 
vegetables  are  sometimes  grown  for  a  time  with  cu- 
cumber plants.  For  details,  see  Chapter  XXI  on  systems 
of  cropping. 

Frame  culture. — The  cucumber  is  well  adapted  to 
frame  culture  and  the  crop  is  largely  grown  in  frames  of 


CUCUMBER  337 

various  descriptions.    See  page  400  for  cultural  directions. 

Insect  enemies. — Various  insects  feed  on  greenhouse 
cucumbers.  One  of  the  most  serious  pests  is  the  red 
spider.  Methods  of  control  are  discussed  on  page  123. 

Unless  preventive  means  are  employed,  the  white  fly 
often  appears  in  such  numbers  as  to  inflict  heavy  losses. 
Either  potassium  or  sodium  cyanide  gas  may  be  used  to 
check  the  ravages  of  this  insect  before  its  depredations 
have  become  serious.  Full  instructions  for  their  use  are 
given  on  page  109. 

Interesting  experiments  were  made  by  Stone  and 
Thomas  at  the  Massachusetts  station,  relative  to  the  in- 
fluence of  various  light  intensities  and  soil  moisture  con- 
tents on  the  development  and  character  of  cucumber 
plant  tissues.  Plants  which  received  the  least  light  and 
the  most  water  were  soft  and  tender  and  much  more  sus- 
ceptible to  injury  from  hydrocyanic  gas  than  were  plants 
which  received  full  light  and  normal  amounts  of  water. 
The  investigators  emphasize  the  importance  of  noting 
the  condition  of  the  plants  before  proceeding  to  fumigate 
with  cyanide.  If  cloudy  weather  and  perhaps  high 
temperatures  have  prevailed  for  a  few  days  and  the 
plants  have  been  supplied  with  an  abundance  of  moisture, 
the  tissues  will  be  soft  and  tender,  and  injuries  will  be 
much  more  likely  to  occur  than  when  the  fumigation 
follows  several  days  of  sunshine  and  normal  conditions 
of  heat,  humidity  and  soil  moisture.  Growers  will  do 
well  to  consider  these  factors  before  fumigating  their 
houses. 

The  nematode  is  regarded  by  most  growers  as  one  of 
the  worst  pests  of  greenhouse  cucumbers.  Sterilization 
with  steam  is  the  usual  method  of  controlling  this  enemy. 
See  page  116. 

The  aphis  is  also  an  enemy  of  greenhouse  cucumbers. 
For  methods  of  control,  see  page  119. 

Fall  and  spring  plants  are  often  attacked  by  the  com- 


338  VEGETABLE  FORCING 

mon  striped  cucumber  beetle.  The  adults  deposit  their 
eggs  on  the  stems  near  or  below  the  surface  of  the 
ground,  where  they  hatch,  and  the  tiny,  transparent 
larvae  feed  on  the  young  roots  and  also  bore  into  the 
stems  of  the  plants.  The  young  insects  do  much  greater 
injury  than  the  beetles.  Serious  attacks  of  this  pest 
sometimes  cause  growers  to  believe  that  the  plants  are 
infected  with  bacterial  wilt.  Preventive  measures  are 
important  in  order  to  guard  against  losses  from  this  pest. 
Cucumbers  and  melons  should  not  be  grown  near  the 
greenhouses,  for  the  beetles  usually  enter  the  houses 
during  the  fall  months  and  remain  well  protected  in  the 
soil  until  the  spring  crop  of  cucumbers  is  started.  It  is  a 
difficult  pest  to  destroy,  and  though  numerous  methods 
might  be  suggested  they  are  not  very  satisfactory.  The 
doors  and  ventilators  should  be  kept  closed,  if  possible, 
in  the  fall,  when  there  is  danger  of  large  numbers  of  the 
insects  entering  the  houses. 

The  squash  bug  or  "stink  bug"  sometimes  feeds  on 
greenhouse  cucumbers.  The  same  preventive  measures 
should  be  taken  as  suggested  in  the  previous  paragraph 
for  the  beetle.  They  inject  a  poisonous  substance  into 
the  plants  and  also  inoculate  them  with  the  dreaded 
disease,  bacterial  wilt.  This  well-known  insect  and  its 
conspicuous  eggs  are  easily  seen  and  they  should  be 
removed  and  destroyed  as  soon  as  discovered.  The 
sciara  maggot,  thrips,  flea-hoppers  and  a  few  other  in- 
sects of  minor  importance  sometimes  appear  on  green- 
house cucumbers. 

Diseases  and  their  control  are  discussed  in  Chapter 
VIII,  and  soil  sterilization  in  Chapter  VI.  The  direc- 
tions in  these  chapters  for  the  prevention  and  treatment 
of  diseases  affecting  greenhouse  vegetables  apply  to  most 
of  the  cucumber  diseases,  so  that  a  lengthy  discussion 
here  is  unnecessary.  All  of  the  troubles  to  which  the 
cucumber  is  subject  when  grown  in  the  open  may  appear 


CUCUMBER  339 

under  glass.  If  the  plants  are  not  stunted  or  checked  in 
growth  at  any  time,  they  are  not  likely  to  become 
diseased. 

Anthracnose  (Colletotrichum  Lagenarium  (Pass.),  E. 
&  H.)  is  a  fungous  disease  which  attacks  the  cucumber  and 
other  cucurbits,  appearing  upon  the  leaves,  stems  and 
fruits.  There  are  times  when  it  becomes  very  trouble- 
some in  the  greenhouse.  Dead  spots  which  are  usually 
more  than  half  an  inch  in  diameter  appear  on  the  leaves, 
and  elongated,  discolored  and  shrunken  areas  occur  on 
the  stems.  The  attacks  may  become  so  serious  as  to  kill 
the  plants.  Either  copper  sulphate  or  bordeaux  mixture 
is  valuable  in  checking  the  ravages  of  the  disease.  The 
dead  vines  at  the  close  of  the  season  should  be  promptly 
removed  from  the  houses  and  burned,  in  order  to  prevent 
the  further  dissemination  of  the  disease. 

The  different  forms  of  "damping-off"  fungi  may  attack 
greenhouse  cucumbers.  Bulletin  214,  Ohio  Experiment 
Station,  says :  "It  is  serious  often  where  plantings  are 
made  following  lettuce  attacked  by  rosette.  The  fungus 
in  that  case  is  the  same  as  lettuce  rosette  (Rhizoctonia) 
or  lettuce  drop  (Sclerotinia).  There  is  a  strictly  damp- 
ing-off fungus  (Pythium  De  Baryanum  Hesse)  that  is 
sometimes  troublesome.  A  species  of  the  Botrytis  fungus 
at  times  attacks  pruned  parts  of  cucumber  plants,  also 
extending  its  attacks  to  the  blossom  ends  of  young  fruits. 
The  results  of  Rhizoctonia  on  greenhouse  cucumbers 
have  been  curious  owing  to  attacks  on  the  smaller  root 
branches  or  rootlets.  The  growth  of  the  vines  is  at  times 
checked,  accompanied  by  coloring  of  the  leaves  and  re- 
duced fruitfulness.  Some  growers  have  given  the  name 
'leaf-curl'  to  this  phenomenon,  but  it  is  strictly  the  effect 
of  the  fungus  named.  It  has  been  found  necessary  in 
soil  treatments  where  cucumbers  follow  affected  lettuce 
to  increase  the  strength  of  formalin  drench  to  four  or  five 
pounds  per  50  gallons  of  water." 


340  VEGETABLE  FORCING 

Downy  Mildew  (Peronoplasmopara  Cubensis  (B.  & 
C.)  Cl.)  is  a  fungous  disease  that  attacks  the  leaves  of  cu- 
cumbers. The  angular,  yellowish  spots  are  followed  by  the 
yellowing  of  the  entire  leaf  and,  if  the  infection  is  severe, 
the  death  of  the  plant  may  occur.  The  cucumbers  on  dis- 
eased plants  are  small  and  inferior  in  quality.  Under 
favorable  conditions  the  disease  develops  and  spreads  to 
other  plants  with  marvelous  rapidity.  It  is  one  of  the  most 
destructive  enemies  of  greenhouse  cucumbers.  Insufficient 
light  and  sunshine,  high  temperatures  and  high  humidity 
are  the  conditions  which  are  most  favorable  to  the  rapid 
development  and  dissemination  of  this  fungous  trouble. 
Spraying  with  bordeaux  mixture  is  valuable,  but  sanitary 
measures  and  the  proper  regulation  of  cultural  conditions 
are  most  important. 

Powdery  Mildew  (Erysiphe  Cichoracearum,  D.  C.)  is 
often  destructive  to  greenhouse  cucumbers  when  conditions 
of  heat,  light  and  moisture  are  favorable  to  the  progress  of 
the  disease.  This  disease  makes  its  appearance  on  the  upper 
surface  of  the  leaves,  where  the  fungus  produces  a  super- 
ficial growth  which  is  powdery  white  in  appearance.  Severe 
attacks  cause  the  plants  to  become  sickly  and  finally  to  die. 
Bordeaux  mixture,  applied  promptly  and  thoroughly,  is 
valuable  in  checking  the  ravages  of  this  disease. 

A  bacterial  wilt  (Bacillus  tracheiphilus,  Smith)  is  often 
found  on  greenhouse  cucumbers.  Most  entomologists 
believe  that  the  disease  is  transmitted  by  the  cucumber 
beetle  and  the  squash  bug.  The  disease  causes  the  plants 
to  wilt  as  if  they  were  suffering  from  the  lack  of  water, 
and  they  finally  die. 

Another  wilt  (Fusarium  niveneum,  Smith)  is  also  fairly 
common  in  the  greenhouse.  It  is  a  fungus  which  works 
internally  in  the  stem  of  the  plant  and  finally  closes  water 
vessels,  thus  interfering  with  the  functions  of  the  stem, 
causing  the  plant  to  wilt  and  die.  This  disease  is  also  trans- 
mitted by  the  cucumber  beetle  and  squash  bug,  and  war 


CUCUMBER 


341 


should  be  waged  on  these  pests,  not  only  for  the  damage 
which  they  may  inflict  by  feeding,  but  also  as  transmitters 
of  these  two  diseases.  Spraying  is  of  no  value  for  either 
of  the  wilts.  .  Infected  plants  should  be  pulled  up  and 
burned. 

Greenhouse  Mosaic  Disease  has  been  studied  by  Selby 
in  Ohio.  Concerning  it  he  writes :  "This  disease  is 
analagous  in  character  to  the  mosaic  disease  of  tobacco 
and  tomatoes  and  to  the  yellows  of  the  peach.  It  is  due 
to  an  oxidizing  ferment  in  the  leaves  and  is  transmitted 
like  the  tobacco  mosaic  disease,  by  touching  first  diseased 
and  then  healthy  plants.  The  fruitfulness  of  these  varie- 
gated yellow  plants  is  very  low,  and  it  is  best  at  all  times, 
upon  the  appearance  of  the  disease,  to  remove  the  dis- 
eased plants  and  destroy  them/' 

Other  diseases  such  as  Leaf  Spot,  Pickle  Spot,  White 
Pickle  or  Mosaic  may  appear  on  plants  growing  under 
greenhouse  conditions,  but  none  of  them  should  prove 


Fig.  120. — Three  grades  of  cucumbers. 


342  VEGETABLE   FORCING 

serious  if  proper  sanitary  measures  are  observed  and  if 
suitable  cultural  conditions  are  maintained. 

Marketing. — After  the  fruits  have  reached  marketable 
size,  it  is  important  to  look  over  the  plants  at  least  three 
times  a  week  so  that  every  cucumber  will  be  picked  at 
the  proper  time.  If  they  are  left  too  long  on  the  vines 
the  seeds  will  become  hard,  which  is  objectionable  from 
the  consumer's  viewpoint;  the  quality  deteriorates  and 
the  color  of  the  rind  becomes  lighter,  a  condition  always 
objectionable  to  both  dealers  and  consumers.  Again,  the 
plants  become  exhausted  more  rapidly  if  the  seeds  are 
allowed  to  develop  to  any  considerable  extent,  and  this 
in  itself  is  an  important  reason  for  early  harvesting. 

The  large  markets  demand  from  two  to  four  grades. 
There  can  be  no  doubt  concerning  the  advantages  of  care- 
ful grading.  Fruits  of  practically  the  same  size,  shape 
and  shade  of  color  should  be  packed  together.  Three 
grades,  besides  the  nubbins,  which  should  be  left  at  home 
unless  there  is  a  local  demand  for  them,  will  be  found 
very  satisfactory.  Fig.  120  will  present  an  idea  as  to  how 
the  fruits  should  be  graded. 

There  are  many  kinds  of  packages  for  the  marketing 
of  cucumbers.  Barrels  holding  three  or  four  bushels  are 
employed  by  some  of  the  Middle  West  growers.  Fig. 
121  shows  some  of  the  packed  barrels  covered  with  bur- 
lap. In  the  Boston  section,  the  bushel  box  (Fig.  122) 
is  the  favorite  package.  It  holds  from  seven  to  nine  dozen 
cucumbers,  the  number  depending  upon  the  size  of  the 
fruits.  The  inside  of  the  box  may  be  lined  with  paper. 
When  closed  with  strips  or  thin  boards,  it  makes  a  very 
satisfactory  package. 

In  some  sections,  crates  holding  four  to  five  dozen 
fruits  are  employed.  Baskets  (Fig.  123)  of  the  same 
kind  and  size  as  those  used  for  packing  lettuce  are  em- 
ployed by  many  New  York,  Pennsylvania  and  Ohio 
growers.  The  baskets  may  be  packed  level  full  so  that 


344 


VEGETABLE  FORCING 


Fig.    122. — Cucumbers   packed  in   bushel   boxes. 

they  can  be  set  on  top  of  one  another  without  danger  of 
bruising  the  fruits.  When  wrapped  with  paper,  the 
basket  makes  a  pleasing  and  satisfactory  package.  A 
basket  holds  from  24  to  30  cucumbers,  the  number  in 
each  being  marked  on  the  handle. 

Yields  and  returns. — There  is  the  widest  variation  in 
the  yields  of  greenhouse  cucumbers.  From  45  to  60 
fruits  to  the  plant  are  expected  by  most  growers  in  the 
Boston  district,  though  much  larger  numbers  are  often 
harvested.  When  a  short  season  is  planned  and  the 
growth  is  limited  to  a  single  stem  with  its  axillary 
branches,  30  fruits  to  the  plant  is  a  good  yield,  especially 
if  the  plants  are  set  close  together. 

With  the  arbor  system  of  training,  as  employed  at 
Rochester,  N.  Y.,  where  the  spacing  is  liberal,  a  single 
plant  may  produce  50  or  more  specimens.  One  house  in 
this  district  containing  550  plants  averaged  nine  dozen 
to  the  plant.  Two  thousand  dozen  cucumbers  of  the  va- 
riety Abundance  from  a  30  by  180-foot  house  is  con- 
sidered a  good  yield  in  the  Rochester  district,  and  as 


CUCUMBER 


345 


many  as  3,500  dozen  have  been  harvested  from  this  area. 
Very  much  depends  upon  the  system  of  training,  spacing, 
variety  and  duration  of  picking  season. 

Cucumbers  during  the  winter  season  sometimes  com- 
mand $2  or  more  a  dozen,  but  such  prices  cannot  be  ob- 
tained for  a  great  length  of  time.  As  the  spring  season 
advances  the  prices  decline  until  in  June  not  more  than 
$1  may  be  obtained,  and  a  large  part  of  the  spring  crop 
is  generally  sold  during  the  summer  at  50  cents  or  less 
per  dozen.  An  average  of  50  cents  for  the  spring  crop 
is  considered  fairly  satisfactory.  Growers  are  sometimes 
forced  to  sell  large  quantities  at  25  to  40  cents  a  dozen. 


Fig.    123. — Cucumbers  packed   in   half-bushel  basket. 


CHAPTER  XIX 
MUSKMELON 

Importance. — In  England  the  muskmelon  is  one  of  the 
most  important  forcing  crops,  being  grown  on  a  large 
commercial  scale  both  in  frames  and  in  greenhouses.  It 
is  produced  most  largely  as  a  spring  and  an  early  summer 
crop.  While  the  cool,  dull,  cloudy  weather  of  England 
is  not  at  all  favorable  to  the  culture  of  this  vegetable, 
which  revels  in  heat  and  sunshine,  the  English  gardeners 
have  become  so  skillful,  and  such  excellent  varieties  have 
been  developed,  that  they  succeed  in  spite  of  adverse 
climatic  conditions.  Melons  have  been  grown  in  the 
greenhouses  of  the  wealthy  in  the  United  States  for  many 
years,  and  private  gardeners  in  America  have  given  much 
more  attention  to  the  crop  than  they  did  only  a  few  years 
ago.  A  host  of  people  are  extremely  fond  of  melons,  and 
it  is  not  surprising  that  private  gardeners  are  urged  to 
give  the  crop  greater  consideration.  The  quality  of  well- 
grown  greenhouse  melons  cannot  be  equaled  by  melons 
produced  out  of  doors  under  the  very  best  conditions. 

As  a  commercial  proposition  in  the  United  States  the 
industry  has  made  very  little  progress.  A  greenhouse 
man  here  and  there  has  tried  small  plantings,  and  some- 
times with  fair  success,  but  they  have  not  been  sufficiently 
encouraged  to  plant  large  areas  for  market  purposes.  It 
is  possible  that  our  growers  have  not  given  the  crop 
enough  attention  to  fully  understand  and  master  every 
detail  in  its  culture,  as  they  have  in  the  growing  of  let- 
tuce, cucumbers  and  tomatoes.  It  is  an  acknowledged 
fact,  however,  that  the  melon  is  much  more  difficult  to 
grow  than  the  other  crops  just  mentioned,  and  that  fancy 
prices  must  be  obtained  in  order  to  realize  a  profit.  The 

til 


MUSKMELON  347 

statement  is  often  made  that  greenhouse  melons  cannot 
be  sold  for  less  than  $1  or  perhaps  $1.50  each  and  enable 
the  grower  even  to  meet  expenses.  Such  prices  certainly 
make  melons  class  as  a  luxury  and  the  demand  for  them 
is  necessarily  limited. 

The  melon,  in  its  cultural  requirements,  is  very  similar 
to  the  cucumber,  though  much  more  exacting.  The  in- 
sect and  fungous  foes  are  also  similar. 

House. — A  greenhouse  which  is  suitable  for  the  forcing 
of  cucumbers  will  be  found  satisfactory  for  growing 
melons.  It  should  be  amply  provided  with  heating  pipes. 
It  should  be  high  enough  to  give  room  for  the  training 
of  the  plants.  Inasmuch  as  the  plants  are  extremely  sen- 
sitive to  cold  drafts  and  sudden  changes  in  temperature, 
small  storm  houses  should  be  provided  wherever  there 
are  outside  doors  that  must  be  used.  Melons  are  gen- 
erally grown  on  raised  benches  provided  with  bottom  heat, 
though  the  spring  crop  may  be  grown  with  entire  success 
in  solid  ground  beds.  Some  growers  prefer  boxes  which 
may  be  placed  on  raised  benches.  A  box  3^  feet  long, 
12  inches  wide  and  8  inches  deep  will  hold  three  plants. 

Varieties. — There  are  numerous  English  varieties  and 
several  American  sorts  that  do  well  under  glass.  Among 
those  which  are  most  frequently  mentioned  are  Sutton's 
Emerald  Gem,  Royal  Jubilee,  Superlative  and  Ring- 
leader. There  are  three  classes  of  melons  according  to 
color  of  flesh,  namely,  green-fleshed,  scarlet-fleshed  and 
white-fleshed.  The  green-fleshed  sorts  are  considered 
the  best  in  quality  by  some,  and  the  scarlet-fleshed  by 
others.  Turner,  in  "Fruits  and  Vegetables  Under 
Glass,"  makes  the  following  classification  :  Green  Flesh : 
Sutton's  Ringleader,  Best  of  All,  Perfection,  Sutton's 
Emerald  Gem,  Windsor  Castle,  Turner's  Seedling,  Royal 
Jubilee,  Emerald  Gem  (American  strain)  ;  Scarlet  Flesh : 
Superlative,  Sutton's  Al,  Sutton's  Scarlet,  Sutton's 
Triumph  and  Sutton's  Invincible;  White  Flesh:  Royal 


348  VEGETABLE  FORCING 

Favorite,  Hero  of  Lockinge  and  Buscot  Park  Hero.  All 
of  these  varieties  are  recommended  by  Turner  of  New 
Jersey,  who  has  had  extended  experience  in  forcing 
melons.  Other  varieties  recommended  by  growers  are 
Blenheim  Orange,  Rocky  Ford  and  Paul  Rose. 

The  utmost  care  should  be  exercised  in  procuring  good 
seed.  Some  of  the  seedsmen,  especially  in  England, 
make  a  specialty  of  producing  pure  strains  of  the  leading 
varieties.  Melons  mix  very  readily  in  the  greenhouse 
where  two  or  more  varieties  are  growing.  If  bees  are 
flying  from  flower  to  flower,  mixing  is  almost  certain  to 
occur,  and  it  is  unlikely  that  the  seed  from  such  crosses 
would  produce  satisfactory  fruits.  If  only  one  variety  is 
used  and  bees  are  not  entering  the  houses  from  outside 
plantations,  there  is  no  reason  why  one  should  not  save 
seed  from  plants  which  are  giving  the  best  results. 

Starting  plants. — Melons  are  started  in  the  same  way 
as  cucumber  plants.  See  page  308.  Seed  may  be  sown  in 
pots,  shifts  being  made  as  explained  for  the  cucumber  on 
page  310,  or  they  may  be  sown  in  beds  or  flats  and  the 
seedlings  pricked  into  pots  or  perhaps  into  beds,  as 
shown  in  Fig.  109.  Whatever  the  method,  the  growth  of 
the  plants  must  not  be  checked  at  any  time,  for  such 
plants  never  recover  and  produce  good  crops.  The 
night  temperature  should  be  from  70  to  75  degrees  and 
the  day  temperature  in  bright  weather  10  to  15  degrees 
higher. 

Seed  should  be  sown  not  later  than  September  1  if  fruit 
is  wanted  for  Christmas.  December  15  is  a  satisfactory 
time  to  sow  for  spring  harvesting  and  later  sowings  will 
produce  early  summer  melons. 

Soil. — While  many  of  the  finest  field  melons  are  pro- 
duced on  sandy  soils,  fairly  heavy  types  of  soil  seem  to 
give  the  best  results  in  the  forcing  of  this  vegetable. 
Some  of  the  best  yields  have  been  obtained  in  clay  soils, 
though  a  moderate  amount  of  sand  mav  be  an  advantage. 


350  VEGETABLE  FORCING 

Fertilizing. — The  fertilizer  requirements  of  the  melon 
and  cucumber  are  very  similar.  Good  melons  cannot  be 
grown  in  a  soil  that  is  not  well  provided  with  plant  food. 
Although  a  fertile  soil  is  essential,  excessive  fertility, 
especially  in  available  nitrogen,  must  be  avoided,  since 
it  will  encourage  a  rank  growth,  and  result  in  the  pro- 
duction of  low  quality  melons.  In  the  preparation  of  the 
soil,  one  should  endeavor  to  supply  nutrients  sufficient  to 
cause  a  healthy,  normal  growth  until  the  fruit  is  set,  and 
then  more  liberal  feeding  should  be  practiced.  Nitrog- 
enous manures  and  fertilizers  used  in  the  preparation 
of  the  beds  should  not  be  employed  in  large  amounts,  if 
at  all.  Among  such  materials  may  be  mentioned  fresh 
horse  manure,  poultry  droppings,  sheep  manure,  nitrate 
of  soda  and  dried  blood.  Well-decayed  manures,  particu- 
larly cow  manure,  may  be  used  in  large  amounts  without 
danger  of  disastrous  results  in  any  respect. 

When  the  fruit  is  set,  then  more  liberal  feeding  is  re- 
quired to  insure  the  production  of  large  melons  and  the 
development  of  high  quality.  A  common  practice  is  to 
employ  at  this  stage  liquid  cow  manure  and  to  apply  it 
as  often  as  may  be  necessary.  The  frequency  of  the 
application  will  depend  mainly  on  the  fertility  of  the  bed. 
Ordinarily,  one  or  two  applications  a  week  will  meet  the 
needs  of  the  plant. 

Some  growers  prefer  to  apply  chemical  fertilizers  after 
the  fruit  is  set,  for  they  claim  that  materials  like  the 
potash  salts,  acid  phosphate  and  nitrate  of  soda  produce 
melons  of  higher  quality  than  does  liquid  cow  manure. 
Wood  ashes  are  sometimes  employed  as  a  top-dressing. 
Lime  is  also  considered  beneficial.  If  the  roots  appear 
in  large  numbers  near  the  surface  of  the  ground,  a  dress- 
ing of  rich  soil  an  inch  deep  will  be  found  beneficial. 

Soil  preparation. — The  English  growers  attach  special 
importance  to  the  use  of  old  sods  in  the  preparation  of 
soil  for  melons.  The  sods  may  be  several  inches  thick. 


MUSKMELON  351 

composted  for  a  month  or  more  and  then  chopped  up 
with  a  spade  into  small  pieces.  Sods  and  manure  may 
be  composted  together,  as  discussed  on  page  72,  and 
sods  are  often  placed  in  the  bottom  of  the  beds  before 
they  are  filled  with  properly  prepared  soil.  While  the 
soil  should  be  firm  and  fairly  compact,  yet  it  must  be 
open  and  porous.  Melon  roots  revel  in  soils  which 
abound  in  vegetable  fiber,  as  provided  by  the  use  of 
chopped  up  sods  and  rotten  manure,  and  the  drainage 
conditions  must  be  perfect.  Because  .of  the  loose  struc- 
ture of  soils  prepared  in  the  manner  described,  it  is  neces- 
sary to  do  more  or  less  packing  of  the  compost  when  the 
beds  are  filled. 

Melons  are  planted  at  about  the  same  distances  as 
cucumbers.  From  15  to  18  inches  between  plants,  and 
the  rows  30  to  36  inches  apart,  will  be  found  satisfactory. 
Planting  distances,  however,  will  depend  mainly  on  the 
system  of  training  which  is  to  be  followed.  The  plants 
should  be  removed  from  the  pots  with  care  so  that  the 
balls  of  earth  will  not  be  broken. 

Watering. — The  melon  requires  an  abundance  of  soil 
moisture,  though  over-watering  must  be  avoided.  It  is 
desirable  to  have  a  liberal  supply  of  moisture  in  the  soil 
when  the  beds  are  planted  and  to  add  enough  water  after 
the  plants  are  set  to  settle  and  compact  the  earth  about 
the  roots.  After  this  operation  no  more  water  should  be 
applied  than  is  necessary  to  maintain  normal,  healthy 
growth  until  the  fruits  are  formed,  and  then  the  plants 
will  require  more  water.  After  the  fruit  has  practically 
attained  full  size  and  the  ripening  process  has  begun,  less 
water  should  be  used,  for  a  superabundance  of  water 
during  the  ripening  period  is  detrimental  to  the  flavor  of 
the  fruit.  The  wilting  of  the  plants  should  not  be  per- 
mitted at  any  time. 

The  humidity  of  the  house  for  melons  seems  to  require 
about  as  much  consideration  as  the  moisture  content  of 


352  VEGETABLE  FORCING 

the  soil.  A  high  humidity  is  essential,  except  when  the 
flowers  are  being  pollenized  and  when  the  fruits  are 
ripening.  It  is  customary  to  sprinkle  the  walks  two  or 
three  times  a  day  in  clear  weather,  and  also  to  syringe 
or  spray  the  plants  with  water  when  atmospheric  condi- 
tions require  such  treatment.  See  notes  on  watering  the 
cucumber,  page  318. 

Temperature. — The  melon  requires  high  and  uniform 
temperatures,  70  to  75  degrees  at  night  and  10  to  15 
degrees  higher  by  day  in  clear  weather. 

Training. — Anyone  who  understands  the  pruning  and 
training  of  cucumbers  (page  324)  should  have  no  diffi- 
culty in  performing  these  operations  with  melon  plants. 
Though  various  systems  are  employed,  probably  the  best 
for  American  greenhouses  is  the  single  stem.  (See  Figs. 
124  and  125.)  That  is,  one  stem  is  grown  to  the  desired 
height — it  may  be  erect — secured  to  a  trellis,  stake  or 
string,  or  it  may  be  trained  over  a  trellis  which  runs 
parallel  to  the  roof  of  the  house.  The  fruits  are  borne 
on  the  laterals  of  the  main  stem,  and  the  laterals  are 
nipped  just  beyond  the  first  leaf.  A  certain  amount  of 
thinning  and  pruning  is  necessary  to  remove  surplus 
leaves  and  to  prevent  the  growth  of  secondary  branches. 
Some  growers  use  divergent  systems  of  training,  as 
explained  for  cucumbers. 

Pollinating. — The  flowers  of  the  muskmelon  are 
monoecious.  They  require  the  same  attention  in  pollinat- 
ing as  does  the  cucumber,  though  this  operation  should 
be  given  closer  attention.  (See  page  329.)  A  camel's  hair 
brush  may  be  employed,  but  a  plan  more  certain  of  suc- 
cess is  to  collect  the  pollen  in  any  convenient  receptacle 
and  then  to  bring  the  pollen  grains  into  direct  contact 
with  the  stigma  of  the  pistillate  flower.  Another  ap- 
proved plan  for  winter  melons  is  to  pluck  a  staminate 
flower,  strip  it  of  the  corolla  and  bring  the  anthers  into 
contact  with  the  stigma  of  the  flower  to  be  pollenized. 


354  VEGETABLE  FORCING 

One  male  flower  will  serve  to  fertilize  two  or  three 
female  flowers,  but  since  the  male  flowers  are  much  more 
numerous,  there  is  no  need  of  economy  in  the  use  of  the 
pollen.  Both  flowers  should  be  fully  expanded  when  this 
work  is  undertaken.  A  bright,  sunny  day  is  preferable, 
and,  as  previously  stated,  the  humidity  of  the  house 
should  be  comparatively  low. 

It  is  highly  important  to  defer  pollinating  until  four 
or  five  -  or  perhaps  more  female  flowers  are  ready  to  re- 
ceive the  pollen.  If  only  one  or  two  flowers  are  pol- 
linated and  no  others  have  attention  for  10  days  or  a 
week  later,  the  first  fruits  will  develop  rapidly  and  those 
which  follow  will  be  small  and  of  poor  quality.  If  all 
the  fruits  on  a  given  plant  set  at  practically  the  same 
time  there  will  be  uniform  development  and  no  one 
specimen  will  be  nourished  more  than  another.  When 
the  melons  attain  considerable  size  they  should  be  sup- 
ported by  a  string  net.  Raffia  is  sometimes  used  to  tie 
up  the  fruit,  but  nets  are  much  more  reliable. 

Ventilation. — See  notes  on  the  ventilation  of  cucumber 
houses.  Even  greater  care  should  be  exercised  in  ven- 
tilating houses  in  which  melons  are  being  forced. 

Insect  enemies. — The  red  spider,  green  aphis,  white 
fly,  striped  cucumber  beetle,  thrips  and  mealy  bug  are 
the  most  destructive  pests.  See  notes  on  cucumber 
pests,  page  337. 

Diseases. — See  diseases  of  cucumber,  page  338.  Pow- 
dery mildew  and  anthracnose  are  among  the  most 
serious  troubles. 

Yields  and  size  of  fruit. — Two  good  melons  on  a  plant 
at  midwinter  is  a  satisfactory  average.  Some  plants  may 
have  four  or  five  and  others  none.  An  average  of  four  or 
five  in  the  spring  is  an  excellent  crop.  The  winter 
melons  may  not  average  m  weight  more  than  two 
pounds.  An  average  of  four  or  five  pounds  to  the  fruit 
is  very  good  for  the  spring  crop.  Six  and  seven-pound 


MUSKMELON  355 

specimens  are  fairly  common,  and  occasionally  eight  to 
ten-pound  melons  are  harvested,  but  the  unusually  large 
melons  are  generally  inferior  in  quality. 

Greenhouse  melons  ripen  very  quickly  after  they  have 
attained  full  size.  They  change  in  color,  emit  a  strong 
but  most  agreeable  perfume  and  separate  easily  from  the 
stem  when  they  are  ripe.  The  fruits  should  not  be  kept 
very  long  in  a  refrigerator  for  this  will  cause  them  to 
deteriorate  rapidly  in  flavor. 

When  melons  are  shipped  they  should  be  unusually 
well  protected  with  cotton,  wool,  excelsior,  or  other 
material  to  prevent  bruising.  It  is  safest  to  use  crates 
provided  with  a  separate  receptacle  for  each  fruit,  in 
which  it  can  be  securely  packed,  so  that  there  can  be  no 
bruising. 


CHAPTER  XX 
MISCELLANEOUS  VEGETABLES 

Although  the  entire  list  of  vegetables  may  be  grown 
successfully  under  glass,  not  all  of  them  yield  satisfactory 
profits  when  forced  for  commercial  purposes.  The  most 
important  ones  have  been  discussed  in  separate  chapters. 
This  volume,  however,  would  not  fulfill  its  purpose  if  it 
did  not  contain  a  chapter  on  the  vegetables  of  minor  im- 
portance as  greenhouse  crops.  While  the  20  vegetables 
considered  in  this  chapter  may  never  attain  the  com- 
mercial rank  of  any  of  the  crops  treated  on  previous  pages, 
yet  some  of  them  are  making  gradual  gains  as  business 
propositions,  and  all  receive  more  or  less  attention  in  the 
greenhouses  of  private  establishments.  Of  the  20  vege- 
tables which  will  be  discussed  in  this  chapter,  only  three 
— the  bean,  the  eggplant  and  the  pepper — can  be  classed 
as  warm  plants,  requiring  comparatively  high  tempera- 
tures day  and  night.  The  others  may  properly  be  called 
cool  plants  because  of  their  relatively  small  heat  require- 
ments. The  entire  list  of  miscellaneous  vegetables  will 
be  discussed  in  alphabetical  order. 

BEAN 

The  bean  is  well  adapted  to  greenhouse  culture,  but 
the  financial  returns  do  not  seem  to  justify  the  planting 
of  large  areas.  Occasionally  an  entire  house  is  planted 
with  this  vegetable,  but  it  does  not  occupy  an  important 
place  in  the  operations  of  greenhouse  growers  in  any 
part  of  the  United  States.  In  England,  where  climatic 
conditions  are  radically  different,  the  forcing  of  beans  is 
a  profitable  enterprise.  It  is  not  unusual  for  them  to  sell 
in  the  London  market  at  Christmas  for  75  cents  to  $1 

356 


MISCELLANEOUS  VEGETABLES  357 

a  pound.  Early  summer  beans  may  retail  for  10  cents  a 
pound.  The  demand  for  forced  beans  in  this  country 
may  increase  rapidly  when  more  of  our  wealthy  con- 
sumers learn  of  the  superior  quality  of  the  greenhouse 
product.  Under  the  controlled  conditions  of  the  green- 
house, the  plants  grow  rapidly  and  produce  large,  tender 
pods  with  a  most  delicious  flavor. 

Beans  may  be  grown  under  glass  throughout  the  forc- 
ing season.  It  is  possible  to  start  the  first  crop  in  Sep- 
tember or  October  and  by  successive  sowings  at  inter- 
vals of  10  days  or  two  weeks  make  continuous  pickings 
until  midsummer  of  the  following  year.  Any  time  after 
March  1  is  the  most  popular  time  for  planting  in  the 
United  States.  The  large  amount  of  sunshine  at  this 
season  of  the  year  is  most  favorable  to  the  rapid  growth 
of  the  plants.  Success  will  be  even  more  certain  if 
planting  is  deferred  until  April  or  May. 

A  common  practice  in  England  is  to  force  beans  in 
pots  not  less  than  6  inches  in  diameter.  Both  pots  and 
boxes  of  various  sizes  are  used  in  the  United  States. 
Most  of  our  growers  prefer  benches  containing  soil  6  to 
8  inches  deep  with  heating  pipes  underneath.  Bottom 
heat  is  absolutely  necessary  for  beans  during  the  winter 
months,  for  they  refuse  to  make  a  satisfactory  growth 
in  cool  soils. 

When  the  spring  is  well  advanced,  the  seed  may  be 
planted  in  solid  ground  beds,  for  the  soil  will  then  be 
warm  enough  to  insure  rapid  growth.  The  bean  requires 
all  the  light  and  sunshine  that  can  be  provided.  It  can- 
not thrive  if  planted  in  the  shade  of  walls,  pipes  or  other 
plants. 

Numerous  varieties  are  grown  under  glass.  Some 
growers  prefer  the  bush  class,  while  others  grow  the  pole 
sorts.  Whatever  the  variety  or  class,  the  plants  should 
make  a  rapid  growth,  come  into  bearing  early  and  pro- 
duce heavy  crops  of  long,  straight,  symmetrical  pods. 


358 


VEGETABLE   FORCING 


Both  wax-podded  and  green-podded  varieties  are  grown 
under  glass.  English  varieties  are  most  generally 
recommended. 

Of  the  American  bush  beans,  Black  Valentine  seems 
to  be  well  adapted  to  forcing.  An  Indiana  grower  has 
obtained  good  results  with  the  Long  Yellow  Six 
Weeks,  which,  with  bottom  heat,  produced  pods  of 
edible  size  in  six  weeks.  A  Tennessee  grower  is  en- 
thusiastic concerning  a  pole  variety  of  local  origin,  sup- 
posed to  be  a  cross  between  Kentucky  Wonder  and  the 
Brown. 


Fig.   126. — Pole  beans  growing  in  an  English  house. 

Of  the  dwarf  English  varieties,  Sutton's  Forcing, 
Osborn's  Forcing,  Ne  Plus  Ultra  and  Canadian  Wonder 
are  most  popular.  English  climbing  or  pole  varieties 
(Fig.  126)  recommended  are  Princess  of  Wales,  Veitchi 
Climbing  French,  King's  Earliest  of  All  and  Wonder  of 
France. 

Bush  beans  are  generally  planted  12  to  15  inches 
apart  in  rows  about  18  inches  apart,  two  or  three  beans 
at  a  place.  If  preferred,  the  beans  may  be  planted  in 


MISCELLANEOUS  VEGETABLES  359 

small  pots  and  then  shifted  to  larger  ones  when  the  roots 
become  crowded.  A  common  practice  is  to  plant  in 
4-inch  pots  and  then  to  shift  to  the  beds  or  benches. 
One  plant  of  a  pole  bean  in  each  place  seems  to  produce 
a  larger  crop  than  two  plants.  The  pole  varieties  may 
be  supported  by  trellises,  twine  or  light  stakes. 

In  general,  greenhouse  beans  require  about  the  same 
cultural  conditions  as  the  cucumber.  The  soil  must  be 
rich,  but  it  should  not  contain  an  excessive  supply  of 
quickly  available  nitrogen.  Fresh  stable  manures  should 
never  be  employed  and  rotten  manures  should  be  well 
mixed  with  the  soil.  Liquid  cow  manure  is  applied  by 
some  growers  after  the  pods  are  formed. 

A  night  temperature  of  60  degrees  will  do,  but  5  to  10 
degrees  higher  will  give  better  results,  and  the  day  tem- 
perature should  range  between  70  and  80  degrees. 
Careful  ventilation  is  necessary.  Sufficient  water  should 
be  applied  to  keep  the  soil  moist,  and  a  moist  atmosphere 
is  also  desirable.  When  the  plants  are  flowering,  a  fairly 
dry  atmosphere  will  aid  the  self-fertile  flowers  to  set  a 
good  number  of  pods. 

The  red  spider,  the  aphis  and  the  white  fly  are  the 
most  serious  pests  of  the  bean  when  grown  as  a  forcing 
crop. 

Growers  cannot  count  on  more  than  two  or  three 
pickings  from  greenhouse  plants.  The  pods  may  be  tied 
in  bundles  of  25  to  50  for  marketing,  or  the  spring  crop 
can  be  sold  in  bulk. 

BEET 

The  beet  is  grown  in  greenhouses,  to  a  limited  extent, 
both  for  greens  and  for  the  roots.  The  soil  should  be 
rich  and  friable.  Temperatures  which  are  suitable  for 
lettuce  will  meet  the  requirements  of  the  beet,  though  it 
grows  more  rapidly  at  higher  temperatures. 


360  VEGETABLE  FORCING 

For  the  fall  crop,  it  is  common  to  sow  in  drills  10 
inches  to  a  foot  apart,  and  to  thin  the  plants  to  2  or  3 
inches  apart.  If  space  is  an  important  consideration,  it 
is  more  economical  to  sow  the  seed  in  beds  or  flats,  and 
then  prick  out  the  seedlings  into  beds  on  the  ground  or 
on  raised  benches.  The  beet  is  sometimes  used  as  a  com- 
panion crop  with  tomatoes  and  cucumbers.  Early  varie- 
ties, such  as  Egyptian,  are  the  most  satisfactory  for 
greenhouse  culture. 

CARROT 

The  carrot  requires  about  the  same  cultural  conditions 
as  the  radish,  except  that  a  larger  percentage  of  sand  is 
needed  to  grow  smooth,  regular  roots.  The  small- 
topped,  early  Short  Horn  type  is  the  best  for  forcing 
purposes.  The  seed  may  be  planted  in  rows  6  inches 
apart  and  the  plants  thinned  to  an  inch  apart.  Sowings 
made  at  intervals  of  three  weeks  will  give  a  succession 
of  roots.  It  does  best  as  a  spring  crop,  though  with 
bottom  heat  it  may  be  grown  with  entire  success  at 
midwinter. 

CHINESE  CABBAGE 

Some  attempts  have  been  made  to  grow  Pe  Tsai  or 
Chinese  cabbage  (Fig.  127)  under  glass,  but  with  only 
fair  success.  It  seems  to  rebel  against  the  artificial  con- 
ditions of  the  greenhouse.  There  is  no  difficulty  in 
growing  the  plants  for  several  weeks,  but  specimens  of 
good  size  tip  burn  very  easily  unless  unusual  precau- 
tions are  taken.  The  transpiration  of  water  from  the 
large,  fleshy  leaves  is  so  rapid  that  the  roots  cannot 
supply  moisture  as  rapidly  as  it  is  lost  from  the  leaves, 
and  tip  burning  necessarily  results.  It  is  thought  that 
a  very  rich  soil  and  low  temperatures  for  about  5  weeks 
would  cause  the  formation  of  an  extensive  root  system, 


MISCELLANEOUS  VEGETABLES 


361 


\ 


Fig.  127. — Chinese  cabbage. 

which,  with  rather  copious  watering  after  that  period, 
would  prevent  the  breaking  down  of  the  tips  of  the 
leaves. 

According  to  experiments  made  by  Hepler  at  the 
University  of  Wisconsin,  12  to  16  weeks  are  required  to 
grow  Chinese  cabbage  to  marketable  size.  It  is  possible 
that  special  strains  of  this  interesting  salad  plant  could 
be  developed  which  would  thrive  well  under  glass.  The 
trouble  is  that  Pe  Tsai  was  never  accustomed  to  green- 
houses in  old  China. 

CRESS 

Water  cress  (Nasturtium  officinale)  is  one  of  the  easiest 
crops  to  grow  in  the  greenhouse.  A  small  planting  of  it 
is  always  desirable  in  private  establishments,  and  com- 
mercial places,  which  are  located  near  markets  that  are 


362  VEGETABLE  FORCING 

not  regularly  supplied  with  cress  from  outdoor  sources, 
find  sale  for  a  limited  quantity. 

Water  cress  may  be  propagated  from  seed  or  cuttings. 
The  usual  plan  in  the  greenhouse  is  to  use  cuttings 
which  root  very  quickly  in  moist  sand.  The  plants  may 
then-  be  shifted  to  flats  and  later  to  the  permanent  beds. 
Bottom  heat  is  unnecessary.  In  fact,  the  plant  does 
better  in  soil  that  is  rather  cool.  The  supply  of  soil 
moisture  should  be  abundant  and  constant.  Water  cress 
may  be  grown  under  benches  where  there  is  fairly  good 
light,  or  in  any  kind  of  a  bed  or  a  box  provided  with 
proper  conditions.  When  well  established,  it  will  renew 
itself  and  require  little  attention,  except  watering. 

CELERY 

Celery  is  not  regarded  in  any  part  of  the  country  as  an 
important  forcing  crop.  It  is  possible,  however,  to  grow 
good  celery  under  greenhouse  conditions,  and  the  diffi- 
culties involved  are  probably  no  greater  than  in  the  pro- 
duction of  some  other  crops — the  melon,  for  example. 
Whether  celery  forcing  will  ever  become  an  important 
commercial  industry  is  extremely  doubtful.  A  grower 
here  and  there  is  fairly  optimistic  concerning  the  out- 
look, but  as  a  financial  proposition  there  is  not  very 
much  encouragement  in  the  results  of  even  the  most  suc- 
cessful greenhouse  growers.  In  general,  it  may  be  said 
that  celery  requires  practically  the  same  conditions  as 
lettuce,  though  it  is  far  more  exacting  in  its  requirements 
of  heat  and  moisture. 

Market  opportunities  seem  to  be  best  during  the 
months  of  April,  May  and  June,  or  after  the  stored 
supply  has  become  exhausted.  To  mature  the  crop  at 
that  time,  the  seed  should  be  sown  the  latter  part  of 
November  or  early  in  December. 

The  so-called  self-blanching  varieties  have  been  al- 
most universally  employed  and  recommended  for  forcing. 


MISCELLANEOUS  VEGETABLES  363 

Bailey,  more  than  25  years  ago,  found  the  Kalamazoo  to 
be  one  of  the  best  varieties  for  culture  under  glass,  and  it 
is  still  recommended  by  practical  growers.  A  few  gar- 
deners speak  enthusiastically  of  White  Plume,  but 
Thorne  found  that  it  had  a  marked  tendency  to  "bolt"  or 
produce  seed  stalks.  He  also  found  that  Golden  Self- 
Blanching  was  a  slow  grower  and  subject  to  heart  rot. 
Of  the  varieties  tested  by  Thorne,  Snow  White  gave  the 
best  results.  A  prominent  greenhouse  grower  at  New 
Castle,  Pa.,  has  had  the  best  success  with  green  varieties. 
Though  they  are  more  difficult  to  blanch,  the  product  is 
of  much  higher  quality  than  that  of  self-blanching 
varieties. 

The  small  plants  grow  very  slowly.  Seed  sown  De- 
cember 1  will  produce  plants  large  enough  for  the  first 
transplanting  by  January  1,  when  they  should  be  set 
about  3  inches  apart  in  flats  or  beds.  In  five  or  six 
weeks  from  transplanting  they  will  be  ready  for  the 
permanent  beds,  which  should  be  on  the  ground  rather 
than  on  benches.  The  plants  should  be  large  enough  to 
market  seven  or  eight  weeks  later. 

There  is  a  difference  of  opinion  among  growers  as  to 
the  most  desirable  distances  for  planting.  The  tendency 
is  to  use  the  "new  celery"  culture  plan,  and  set  the  plants 
6  inches  by  6  inches  or  7  inches  by  7  inches  apart. 
Others  claim  better  results  by  allowing  15  inches  or  16 
inches  between  rows,  and  by  placing  the  plants  about  4 
inches  apart  in  the  rows.  The  latter  plan  is  probably 
best  for  green  varieties. 

Celery  requires  an  abundant  supply  of  moisture 
throughout  the  period  of  growth.  A  deficiency  of 
moisture  at  any  time  is  likely  to  prove  disastrous.  Ex- 
cessively high  or  very  low  temperatures  are  also  de- 
cidedly objectionable,  for  either  condition  may  cause  a 
large  percentage  of  the  plants  to  produce  seed  shoots. 


364 


VEGETABLE   FORCING 


To  avoid  this  loss,  the  plants  should  not  be  checked  in 
growth  at  any  time. 

The  commonest  plan  of  blanching  is  to  enclose  the 
plants  with  hard,  durable  paper.  A  6-inch  strip  is 
wrapped  tightly  around  each  plant  just  as  soon  as  the 
stems  are  large  enough  for  the  leaves  to  extend  a  few 
inches  above  the  top  of  the  paper.  About  three  weeks 
later  it  is  necessary  to  tie  another  strip  of  paper  above 
and  around  the  same  plant  so  that  it  overlaps  the  first 
strip. 

DANDELION 

The  dandelion  (Fig.  128)  is  forced,  to  some  extent,  in 
greenhouses  for  greens.  It  is  quite  an  important  frame 
crop  near  Boston.  Crowns  are  grown  out  of  doors  from 
spring-sown  seed  and  then  planted  in  the  greenhouse  or 


Fig.   128. — Dandelion  being  forced  in   a  cheap  house  near  Boston. 

in  frames  for  forcing.  The  plants  may  be  set  4  inches 
by  8  inches  apart.  All  that  is  necessary  is  to  provide  an 
abundant  and  uniform  supply  of  soil  moisture  and  tem- 
peratures which  would  be  suitable  for  lettuce.  Some- 
times the  crowns  are  set  in  inexpensive  sash  houses  during 
the  fall,  but  the  sash  are  not  placed  on  the  houses  until 


MISCELLANEOUS  VEGETABLES  365 

it  is  desired  to  force  the  crop.    A  few  coils  of  pipe  will 
provide  the  required  amount  of  heat  for  this  hardy  plant. 

EGGPLANT 

It  is  a  simple  matter  to  grow  the  eggplant  under  glass. 
For  many  years  it  has  been  forced  in  private  establish- 
ments, and  it  has  attracted  attention  occasionally  for  its 
business  possibilities.  The  spring  crop — the  fruits  being 
harvested  during  the  months  of  May,  June  and  July — 
seems  to  be  the  most  promising  as  a  business  venture, 
largely  because  weather  conditions  at  this  season  are 
more  favorable  for  the  production  of  a  crop  that  requires 
plenty  of  sunshine. 

Any  of  the  varieties  may  be  grown  under  glass,  but  the 
large,  purple-fruited  type  is  the  most  desirable.  New 
York  Improved  is  probably  one  of  the  best  varieties  for 
greenhouse  culture. 

In  the  spring  of  the  year  a  little  more  time  is  required 
from  seed  sowing  to  ripened  fruit  than  is  needed  for  the 
tomato.  Seed  sown  February  1  should  produce  plants  in 
full  bearing  in  June. 

The  plants  require  a  large  amount  of  heat,  fully  as 
much  as  cucumbers,  throughout  the  period  of  growth. 
Night  temperatures  should  never  be  below  65  degrees 
and  day  temperatures  with  sunshine  may  run  up  to  80 
degrees  or  higher  if  the  ventilators  are  open.  Cold  drafts 
and  sudden  changes  in  temperature  should  be  carefully 
avoided,  for  unchecked  growth  is  one  of  the  most 
important  factors  in  producing  a  successful  crop. 

The  seed  may  be  sown  in  flats  or  in  a  warm  bed,  and 
in  about  four  weeks  the  plants  should  be  set  in  2^-inch 
pots.  As  soon  as  the  pots  become  well  filled  with  roots 
the  plants  should  be  shifted  to  4  or  5-inch  pots  and  later 
to  the  beds,  space  between  plants  being  2  feet  apart  each 
way.  Raised  benches  with  bottom  heat  should  be  used 


366  VEGETABLE  FORCING 

for  winter  forcing,  but  the  spring  crop  does  very  well  in 
solid  ground  beds. 

The  soil  for  eggplants  should  be  sandy  if  possible  and 
well  enriched  with  rotten  manure.  This  plant  makes  the 
most  rapid  growth  and  produces  the  largest  fruits  when 
the  soil  is  filled  with  decaying  vegetable  matter. 

The  eggplant  does  not  need  a  large  amount  of  water. 
It  thrives  best  when  the  soil  is  only  fairly  moist. 

No  trimming  or  tying  is  necessary,  but  the  pollination 
of  the  flowers  must  have  careful  attention.  The  fruits 
set  without  being  fertilized,  but  they  never  develop  to 
edible  size.  Hand  pollination,  as  explained  for  melons, 
page  352,  is  most  thorough  and  unquestionably  the  best 
method  for  winter  eggplants,  but  bees  (page  332)  are 
satisfactory  for  the  spring  crop. 

The  eggplant  is  subject  to  the  attack  of  most  of  the 
greenhouse  insect  pests,  and  only  constant  vigilance  will 
prevent  serious  injuries. 

KOHL-RABI 

A  few  greenhouse  growers  have  tried  kohl-rabi  (Fig. 
129),  and  some  report  that  the  profits  are  at  least  fairly 
satisfactory.  The  plants  are  started  in  the  same  way  as 
cabbage.  Seed  may  be  sown  in  beds  or  flats  and  the 
plants  at  three  or  four  weeks  of  age  pricked  into  flats.  A 
month  later  they  will  be  ready  for  the  ground  beds,  or  the 
raised  benches.  Six  to  8  inches  between  plants  will  pro- 
vide space  for  the  development  of  good  roots.  White 
Vienna  is  an  excellent  forcing  variety.  The  tender  stems 
are  of  the  highest  quality. 

MINTS 

The  different  kinds  of  mint,  especially  sage  and  spear- 
mint, are  easily  grown  in  greenhouses  which  provide 
about  the  same  conditions  of  heat  and  moisture  as  are 


MISCELLANEOUS  VEGETABLES 


367 


Fig.  129.— Kohl-rabi  at  the  Ohio  State  University. 

required  for  lettuce.  If  desired,  special  plants  may  be 
grown  in  the  open  and  transferred  to  the  house  in  the  fall. 
The  demand  for  mint  is  very  limited. 

MUSTARD 

Mustard  is  grown  under  glass,  to  a  limited  extent,  for 
salad  purposes  and  also  for  greens.  Chinese,  a  broad- 
leafed  variety  well  adapted  to  greenhouse  culture,  will 
make  more  herbage  than  any  other  variety.  The  most 
economical  use  of  space  is  to  start  the  plants  in  flats  and 
transplant  seedlings  of  large  size  into  beds  where  the  crop 
is  to  be  grown.  The  plants  may  be  set  6  to  8  inches 
apart.  Mustard  requires  practically  the  same  cultural 
conditions  as  lettuce. 

ONION 

The  onion  is  forced  to  some  extent  for  commercial  pur- 
poses. It  requires  the  same  conditions  of  heat  and  mois- 
ture as  lettuce,  though  it  is  more  hardy.  Sets  of  any  of 


368  VEGETABLE   FORCING 

the  varieties  may  be  used  for  forcing,  but  the  Egyptian  or 
Top  onion  is  most  generally  employed.  It  is  an 
extremely  hardy  onion  that  endures  the  hardest  freezing. 
An  Ohio  grower  describes  his  method  as  follows  in  the 
Market  Growers'  Journal: 

"I  plant  the  largest  sets  I  can  get  in  the  open  ground  early  in 
September,  2  inches  deep,  4  or  5  inches  apart  in  the  row,  and  the 
rows  14  or  15  inches  apart.  These  will  make  a  nice  growth  before 
cold  weather  sets  in  and  winter  nicely  without  protection.  I  culti- 
vate the  following  summer  just  as  any  other  garden  crop,  and  harvest 
the  sets  during  July  or  August.  After  the  top  sets  have  been  har- 
vested we  cut  the  old  stem  off  about  1  inch  below  the  surface  of 
the  ground.  This  leaves  the  ground  level  and  ready  for  the  mulch- 
ing which  is  the  secret  of  long  green  onions  for  bunching.  We 
cover  the  entire  surface  with  coarse  manure  4  or  5  inches  deep, 
just  as  it  comes  from  the  livery  stable.  We  are  careful  that  no 
heavy  bunches  of  manure  lie  directly  on  the  row.  Within  a  few 
weeks  the  onions  are  through  the  mulch  and  make  a  number  of 
long,  green  shoots  from  fa  to  fa  of  an  inch  in  thickness  and  from 
12  to  20  in  number.  Roots  and  all  are  harvested  in  the  late  fall 
just  before  hard  freezing  sets  in,  and  stored  in  any  protected  place. 
"We  use  unoccupied  coldframes  and  pack  as  closely  as  the  onions 
can  be  set,  with  a  little  earth  between  the  rows,  packed  well  against 
the  roots.  This  gives  us  access  to  them  at  any  time  in  the  winter. 
We  begin  forcing  about  December  1  by  placing  them  under  our 
propagating  benches  in  the  greenhouse,  always  in  a  perpendicular 
position  to  avoid  having  them  grow  crooked.  We  allow  about  three 
weeks  for  the  first  setting  to  grow  a  new  top  and  to  be  ready  for 
our  market.  Toward  spring,  less  time  is  required  for  them  to  attain 
marketable  size.  They  grow  so  rapidly  when  placed  in  a  house  that 
only  a  few  can  be  put  in  at  one  time.  We  put  in  new  stock  each 
day  when  we  take  out  any  for  sale." 

Sometimes  the  garden  beds  of  sets  are  heavily  mulched 
during  the  winter,  dug  early  in  the  spring  and  taken  to 
the  greenhouse  for  forcing.  Another  plan  is  to  plant  the 
top  sets  in  August  or  early  in  September.  Before  the 
ground  freezes  late  in  the  fall  the  sets  are  dug  and 
heeled  in  close  together  in  a  cool  shed,  from  which  they 


MISCELLANEOUS  VEGETABLES  369 

are  taken  as  wanted  to  the  greenhouse  and  planted  in  the 
beds.  Whatever  kind  of  sets  or  bulbs  may  be  used,  they 
should  be  planted  very  close  together  in  order  to  obtain 
a  heavy  and  profitable  crop.  It  is  also  desirable  to  plant 
deep  so  as  to  produce  long,  well-blanched  stems. 

PARSLEY 

There  is  always  some  demand  for  parsley.  The  leaves 
are  tied  in  small  bunches,  which  generally  retail  at  about 
5  cents  a  bunch.  Plants  for  forcing  purposes  are  grown 
in  the  open  ground  from  seed  sown  early  in  the  spring. 
The  seed  should  be  sown  in  drills  and  the  seedlings 
thinned  to  stand  not  less  than  10  inches  apart,  if  strong 
plants  are  desired.  In  the  fall  of  the  year,  any  time  before 
there  is  hard  freezing,  the  plants  are  cut  back  to  the 
crown  and  the  roots  planted  in  the  greenhouse.  If  con- 
ditions of  heat  and  moisture  are  provided  which  would 
be  suitable  for  lettuce,  new  leaves  will  soon  develop  and 
these  may  be  cut  from  week  to  week  until  the  plants  are 
exhausted.  The  plants  are  easily  grown  from  seed  sown 
in  the  greenhouse  early  in  the  fall.  Any  of  the  curly- 
leafed  varieties  may  be  used  for  forcing. 

PEA 

The  pea  is  not  a  profitable  forcing  crop,  though  it  is 
easily  grown  under  glass.  The  early,  dwarf  varieties  are 
preferred  for  forcing.  Nott's  Excelsior  is  a  dwarf, 
wrinkled  variety  of  superior  quality  and  it  is  probable 
that  this  variety  would  thrive  just  as  well  under  glass 
as  the  smooth,  extremely  early  sorts.  The  soil  should  be 
deep  and  rich.  A  large  proportion  of  rotten  manure  is 
valuable  in  securing  a  full  crop. 

The  distance  between  rows  will  depend  on  the  space 
requirement  of  the  variety  planted.  Under  greenhouse 
conditions,  12  to  15  inches  between  rows  should  provide 


370  VEGETABLE  FORCING 

ample  space  for  dwarf  varieties,  especially  if  they  are 
well  supported  by  wires  or  by  some  other  means.  Peas 
should  have  a  night  temperature  of  40  to  50  degrees  and 
a  day  temperature  of  55  to  60  degrees.  The  plants  are 
very  sensitive  to  heat  and  no  attempt  should  be  made  to 
continue  the  crop  after  April  1.  They  grow  better  in 
solid  ground  beds  than  on  raised  benches,  and  plenty  of 
water  must  be  supplied  during  the  entire  period  of  forc- 
ing. The  forcing  of  peas  is  seldom  undertaken  in 
commercial  establishments. 

PEPPER 

The  pepper  is  not  forced  to  any  considerable  extent  in 
either  commercial  or  private  establishments.  The  fruit 
of  this  vegetable  stands  shipment  much  better  than  the 
tomato,  so  that  southern  competition  prevents  the  de- 
velopment of  pepper  forcing  in  the  North.  However,  it 
is  not  a  difficult  crop  to  grow  under  glass.  The  plants 
are  started  in  the  same  manner  as  tomatoes,  and  then 
shifted  from  3  or  4-inch  pots  to  the  beds  where  the  crop 
is  to  mature.  The  distance  between  plants  in  the  beds 
should  be  determined  by  the  space  requirements  of  the 
variety  selected.  A  foot  between  plants  in  the  row  is 
generally  space  enough  for  them,  and  the  rows  need  not 
be  more  than  18  inches  apart.  Experiments  at  Cornell 
University  seemed  to  indicate  that  the  plants  grow  best 
at  temperatures  slightly  lower  than  those  required  for 
melons  and  cucumbers,  though  excellent  results  were 
obtained  in  the  same  houses.  The  plants  produced 
marketable  specimens  in  3^  months  from  seed  sowing. 
Sweet  Mountain  was  the  favorite  variety  in  the  Cornell 
experiments.  It  is  important  to  force  pure  strains  of 
the  best  sweet-fruited  sorts.  Artificial  pollination, 
according  to  the  Cornell  observations,  is  unnecessary. 


MISCELLANEOUS  VEGETABLES  371 

SEA  KALE 

Sea  kale  is  an  important  forcing  crop  in  European 
countries.  It  is  grown  under  glass  to  some  extent  in  this 
country,  and  it  would  seem  that  the  vegetable  should 
have  greater  consideration  by  those  who  are  endeavoring 
to  diversify  their  operations. 

The  plants  are  readily  propagated  from  seed  or  root 
cuttings.  Root  cuttings  are  preferred  by  some  growers, 
but,  for  the  production  of  crowns  for  forcing,  seed  is  en- 
tirely satisfactory.  Two  seasons  are  required  to  grow 
the  strongest  forcing  roots.  The  seed  should  be  sown  in 
rich  soil  as  early  in  the  spring  as  the  ground  can  be 
worked.  The  drills  should  be  about  2  feet  apart  and  the 
plants  thinned  to  stand  at  intervals  of  6  to  8  inches.  A 
vigorous  growth  should  be  encouraged.  The  following 
spring  the  plants  should  be  transplanted  3  by  3  feet  apart 
into  soil  of  high  fertility. 

Special  feeding  as  provided  by  a  manure  mulch  or 
dressings  of  nitrate  of  soda  will  be  found  beneficial.  The 
seed  stalks  should  be  removed  whenever  they  appear. 
Any  house  which  provides  suitable  temperatures  for 
lettuce  will  meet  the  requirements  of  sea  kale.  The 
plants  may  be  forced  under  greenhouse  benches,  in  mush- 
room houses  and  other  inexpensive  structures,  such  as 
were  described  on  page  195  for  the  forcing  of  rhubarb. 
The  crowns  are  set  as  close  together  as  possible,  in  the 
dark  if  desired,  with  fine  soil  filling  all  spaces  between  the 
roots.  Sufficient  water  is  applied  to  keep  the  soil  moist. 
The  crisp,  tender  leaves  are  picked  whenever  they  attain 
a  length  of  4  to  6  inches.  When  the  plants  are  lifted  in 
the  field  at  the  end  of  the  second  season,  the  crown  buds 
should  be  cut  out  to  prevent  the  plants  from  producing 
seed. 


372  VEGETABLE  FORCING 

SPINACH 

There  is  some  inclination  among  the  greenhouse 
growers  of  the  United  States  to  commercialize  the  forcing 
of  spinach.  For  example,  Waid  calls  attention,  in  the 
Market  Growers'  Journal,  to  a  Grand  Rapids  grower  who 
has  been  producing  spinach  under  glass  for  several  years 
and  who  has  found  the  crop  as  profitable  at  10  cents  a 
pound  as  lettuce.  A  bed  at  Grand  Rapids,  15  by  150 
feet  in  area,  yields  in  a  single  crop  from  1,500  to  2,000 
pounds  of  spinach,  which  is  sold  for  $1.25  to  $1.50  a 
bushel  of  15  pounds.  The  weight  of  the  crop  from  a 
given  area  is  about  the  same  as  for  lettuce. 

A  number  of  varieties  have  been  suggested  for  forcing. 
The  vigorous,  broad-leafed  sorts  seem  to  be  most  popu- 
lar. Victoria  and  New  Zealand  are  recommended,  and 
the  latter  variety  is  of  special  merit.  Spinach  seed  germi- 
nates very  slowly,  and  time  and  space  may  be  saved  by 
soaking  the  seed  before  it  is  sown.  An  excellent  plan  is 
to  mix  it  with  moist  sand  and  place  it  in  a  covered  dish 
which  is  kept  over  warm  pipes  for  a  week  or  10  days, 
when  the  seeds  will  start  to  sprout  and  should  then  be 
sown.  It  is  important  to  note  in  this  connection  that 
spinach  is  easily  transplanted.  There  is  no  reason  why 
the  plants  cannot  be  started  in  flats  or  beds  in  the  same 
manner  as  lettuce  and  then  set  in  the  beds  where  the  crop 
is  to  mature.  The  best  planting  distances  have  not  been 
determined,  but  it  is  probable  that  the  rows  should  be  8 
to  10  inches  apart. 

Spinach  requires  the  same  cultural  treatment  as  lettuce. 
High  temperatures  should  be  avoided.  The  beds  should 
be  kept  moist,  and  the  surface  cultivated  when  necessary. 
There  should  be  no  shortage  in  plant  food  at  any  time. 
Applications  of  nitrate  of  soda  will  prove  beneficial  un- 
less the  soil  is  well  supplied  with  nitrogen.  Rapid  growth 
is  essential  to  high  quality. 


MISCELLANEOUS  VEGETABLES  373 

SWISS  CHARD 

Swiss  chard  is  popular  as  greens,  which  offers  possi- 
bilities for  greenhouse  culture.  It  requires  practically 
the  same  treatment  as  lettuce.  The  seed  may  be  sown  in 
drills  where  the  crop  will  be  matured,  or  time  and  space 
may  be  saved  by  starting  the  plants  in  flats  in  the  same 
manner  as  lettuce.  High  fertility  and  an  abundant  mois- 
ture supply  are  essential  to  heavy  yields  and  good  quality. 
The  leaves  may  be  picked  whenever  they  have  attained 
the  size  desired,  and  new  ones  will  continue  to  grow  out 
from  the  heart  of  the  plant  during  the  entire  forcing 
season.  Lucullus  is  one  of  the  best-known  varieties. 
Large  plants  in  the  garden  may  be  cut  back  in  the  fall 
and  transferred  to  the  greenhouse  beds.  It  is  likely,  how- 
ever, that  younger  plants  will  give  better  results  for 
midwinter  forcing. 

TURNIP 

It  is  a  simple  proposition  to  grow  turnips  in  green- 
houses where  conditions  are  suitable  for  the  forcing  of 
lettuce.  Early  varieties  should  be  employed.  The  drills 
should  be  8  to  10  inches  apart  and  the  plants  thinned  to 
about  2  inches.  Turnip  tops  are  sometimes  grown  for 
greens  from  large  roots  planted  close  together.  The 
leaves  should  be  blanched  in  order  to  secure  the  highest 
quality.  Leaves  of  edible  size  may  be  grown  in  three 
weeks. 

WITLOOF  CHICORY 

This  vegetable  is  one  of  the  most  important  salad  crops 
of  France,  Belgium  and  England.  It  is  variously  known 
as  witloof  chicory,  French  endive  and  English  endive. 
Perhaps  the  most  appropriate  name  is  witloof  chicory, 
because  it  is  a  development  of  the  common  chicory. 

Until  the  great  European  war  broke  out  in  1914,  thou- 
sands of  baskets  were  imported  every  year  from  France 


374 


VEGETABLE  FORCING 


and  Belgium  to  the  United  States.  Since  that  time  and 
on  account  of  transportation  difficulties  and  the  scarcity 
of  the  product,  American  gardeners  have  become  more 
interested  in  the  crop  and  some  of  them  are  making  it  an 
important  factor  in  their  operations.  Wholesale  prices 
in  this  country  previous  to  the  war  probably  averaged 
from  25  to  30  cents  a  pound,  while  more  than  double  this 
price  has  been  obtained  since  the  supply  has  been  so 
greatly  decreased. 

There  can  be  no  doubt  concerning  the  superior  merits 
of  witloof  chicory  as  a  salad  plant.  It  does  not  appeal  to 
all  alike,  but  most  people  are  very  fond  of  the  vegetable 
and  do  not  need  to  cultivate  a  taste  for  it.  The  heads  or 
shoots  (Fig.  130)  are  creamy  white  in  color,  extremely 

tender,  crisp,  delicate  and 
agreeable  in  flavor.  Though 
it  is  generally  used  as  a 
salad,  seasoning  and  flavor- 
ing it  in  any  manner  that 
may  be  desired,  the  heads 
may  also  be  cooked  before 
they  are  served. 

There  can  be  no  question 
about  this  vegetable  afford- 
ing  opportunities  to  the  com- 
mercial growers  of  the 
United  States.  Our  markets 
are  poorly  supplied,  and  the 
demand,  as  the  vegetable  be- 
comes better  known,  will  in- 
crease. Many  of  the  Ameri- 
can gardeners  have  probably 
thought  that  there  was  some- 
thing peculiarly  difficult  or 
mysterious  about  the  culture 
Fig.  130.— witioof  chicory.  of  witloof  chicory,  but  we 


MISCELLANEOUS  VEGETABLES  375 

have  learned  that  the  crop  is  no  more  difficult  to  grow 
than  many  other  vegetables  which  receive  our  attention 
and  contribute  to  our  earnings. 

The  roots  for  forcing  are  grown  in  the  open.  The  soil 
should  be  deep,  rich  and  moist,  but  well  drained.  Any 
soil  which  will  grow  good  parsnips  will  produce  good  wit- 
loof  roots.  Liberal  amounts  of  rotten  manure  (fresh 
manure  should  never  be  used)  are  valuable  in  growing 
large  roots,  and  large  roots  are  necessary  for  growing 
large  heads.  Small,  crooked,  inferior  roots  never  produce 
a  first-class  product. 

Care  should  be  exercised  in  buying  seed.  If  ordinary 
chicory  seed  is  obtained,  the  results  will  be  most  dis- 
appointing. A  pure  forcing  strain  is  essential  to  success. 
If  the  seed  is  sown  too  early  in  the  spring,  a  large  per- 
centage of  the  plants  may  go  to  seed,  and  the  roots  of 
such  plants  will  not  do  for  forcing.  Again,  roots  started 
too  early  in  the  spring  do  not  seem  to  possess  the  vitality 
of  younger  roots.  While  the  seed  may  be  sown  any  time 
during  the  month  of  May,  there  is  evidence  that  just  as 
good  and  perhaps  better  roots  may  be  grown  from  seed 
sown  about  June  1,  or  even  a  week  or  two  later. 

The  rows  should  not  be  closer  than  15  inches,  and  18 
inches  between  rows  in  rich  soil  will  give  better  results. 
If  the  crop  is  to  be  cultivated  with  a  horse,  not  less  than 
28  inches  should  be  allowed  between  rows.  Some  grow- 
ers advocate  thinning  the  plants  to  stand  6  to  8  inches 
apart,  but  this  seems  to  be  more  space  than  is  really 
needed  to  grow  large  roots,  especially  if  the  soil  is  fertile. 
If  the  plants  stand  at  intervals  of  4  to  5  inches,  the  re- 
sults should  be  highly  satisfactory.  The  crop  should 
have  thorough  tillage  throughout  the  summer  and  early 
fall.  The  plants  are  just  as  easy  to  grow  as  are  parsnips. 

The  roots  should  be  dug  as  late  as  possible  in  the  fall, 
but  before  the  ground  is  frozen.  The  tops  are  cut  back 
within  an  inch  of  the  crowns  and  the  roots  are  then 


376  VEGETABLE  FORCING 

stored  in  a  cool  shed,  frame  or  cellar  where  they  can  be 
kept  fairly  moist  and  perfectly  dormant.  Storage  condi- 
tions which  are  suitable  for  asparagus  roots  (page  182) 
will  be  satisfactory  for  withloof  roots. 

Witloof  chicory  may  be  forced  tinder  greenhouse 
benches,  in  cheaply  constructed  houses,  as  explained  for 
rhubarb  and  asparagus,  in  cellars  and  in  out-of-door 
trenches.  A  temperature  of  50  to  60  degrees  will  meet 
the  requirements  of  the  crop.  Higher  temperatures  cause 
the  growth  of  long  shoots,  and  the  total  weight  of  the 
crop  will  be  less  than  when  it  is  grown  at  lower  tempera- 
tures. 

The  roots,  of  course,  may  vary  considerably  in  size. 
This  necessitates  grading  them  according  to  size  before 
they  are  planted.  In  deep,  rich  soils  some  of  the  roots 
will  be  nearly  a  foot  long,  while  others  may  be  not  more 
than  half  that  length.  It  is  best  to  make  about  four 
grades.  Each  grade  is  also  cut  to  an  approximately 
uniform  length.  That  is,  the  slender  tips  are  cut  off  so  as 
to  make  each  grade  of  roots  about  the  same  length ;  the 
crowns  will  then  be  on  the  same  level  when  the  roots  are 
placed  in  the  beds. 

The  roots  may  be  taken  from  storage  at  any  time  from 
late  fall  until  spring.  In  order  to  secure  a  succession  of 
heads  or  shoots,  new  plantings  should  be  made  every 
week  or  two.  An  inch  or  two  of  soil  is  placed  in  the 
bottom  of  the  bed.  The  roots  are  then  arranged  to  stand 
erect.  (Fig.  131.)  There  is  some  difference  of  opinion 
as  to  the  spacing  of  the  roots,  but  there  can  be  no  serious 
objection  to  placing  them  so  close  together  that  they 
almost  touch.  It  is  likely  that  the  best  results  will  be 
obtained  if  each  root  is  completely  surrounded  with  moist 
soil  or  sand.  This  is  easily  sifted  between  them  as  the 
planting  proceeds. 

In  order  to  blanch  the  shoots  or  heads  and  to  make 
them  grow  compact,  as  shown  in  Fig.  130,  it  is  necessary 


MISCELLANEOUS  VEGETABLES 


377 


Fig.    131. — Planting  witloof  chicory   in   trenches. 

to  cover  the  crowns  with  fine  soil,  sand  or  sawdust. 
Sand  is  probably  the  favorite  material.  For  the  early 
crop  this  need  not  be  more  than  4  or  5  inches  deep,  but 
ordinarily  from  6  to  8  inches  of  sand  should  be  placed 
over  the  crowns,  after  they  have  had  a  thorough  soaking 
with  water.  One  or  two  additional  waterings  may  be 
needed,  or  several  waterings  if  the  evaporation  of  mois- 
ture from  the  beds  is  very  rapid.  If  there  are  compara- 
tively high  temperatures,  shoots  may  appear  at  the 
surface  of  the  sand  in  two  weeks,  when  they  are  ready  to 
cut,  though  three  to  four  weeks  are  usually  required. 

Most  excellent  witloof  may  be  grown  in  out-of-door 
trenches.     They  should  be  about  18  inches  deep  and  15 


378  VEGETABLE  FORCING 

inches  wide.  The  roots  are  planted  as  explained,  and 
covered  with  sand  in  the  usual  manner.  Heat  is  provided 
by  covering  the  trench  with  2  feet  of  hot  horse  manure, 
which  should  extend  about  1^  feet  on  either  side  of  the 
trench.  With  this  method,  about  a  month  is  required 
for  the  shoots  to  grow  through  8  inches  of  sand. 

If  desired,  the  trenches  may  be  dug  in  the  fall,  the  roots 
planted  at  once  and  the  hot  manure  used  at  any  time 
during  the  winter.  In  this  instance,  the  trenched  roots 
should  be  covered  sufficiently  with  manure  in  the  fall  to 
prevent  hard  freezing. 

When  a  crop  sells  at  25  cents  or  more  a  pound,  special 
care  should  be  exercised  in  preparing  it  for  market. 
Though  most  of  the  French  and  Belgian  product  is 
shipped  in  20-pound  baskets,  smaller  packages  would  be 
an  advantage,  especially  when  the  crop  is  selling  at  very 
high  prices.  It  would  seem  that  pound  lots,  wrapped  in 
paraffined  paper  and  packed  in  small  baskets,  would 
appeal  to  dealers  as  well  as  to  consumers. 


CHAPTER  XXI 
SYSTEMS  OF  CROPPING 

Necessity  of  intensive  methods. — The  student  who  has 
followed  the  discussions  of  previous  chapters  has  doubt- 
less observed  that  vegetable  forcing  is  a  most  intensive 
type  of  horticulture.  It  calls  for  large  expenditures  of 
capital  and  labor  upon  relatively  small  areas.  The  invest- 
ment on  one  acre  of  land  may  be  greater  than  on  a  farm 
of  100  acres. 

The  first  cost  of  the  land  is  a  small  factor.  But  the 
range  of  houses  with  its  equipment  of  boilers,  heating 
pipes,  water  lines,  packing  room,  etc.,  may  represent 
thousands  of  dollars,  though  it  may  be  a  mere  garden 
patch  in  size.  Furthermore,  we  must  bear  in  mind  that 
the  cropping  operations  themselves  are  far  more  expen- 
sive than  similar  lines  of  work  in  the  field  or  garden.  Every 
need  of  the  crop  must  be  met  by  the  employment  of  arti- 
ficial methods.  Large  amounts  of  fuel  must  be  consumed 
annually.  Even  the  water  must  frequently  be  paid  for, 
in  addition  to  the  labor  involved  in  applying  it.  Tem- 
peratures must  be  regulated  and  the  ventilators  operated 
as  often  as  may  be  necessary.  It  is  necessary  to  maintain 
the  highest  fertility  of  the  soil,  and  sometimes  to  sterilize 
it  in  order  to  prevent  diseases  or  insects  pests  from  gain- 
ing the  upper  hand.  Some  of  the  vegetables  require 
special  attention  in  the  way  of  pruning,  training,  pollinat- 
ing and  spraying.  The  houses  require  more  or  less  atten- 
tion annually  in  order  to  keep  them  in  good  repair,  and  the 
interest  on  the  investment  and  the  depreciation  in  the 
value  of  the  range  and  equipment  must  also  have  con- 
sideration. 

An  enumeration  of  the  foregoing  factors  is  given  not 

379 


380  VEGETABLE  FORCING 

with  a  view  to  discouraging  any  one,  but  they  should  be 
seriously  considered  before  launching  into  the  business 
of  vegetable  forcing.  They  call  for  the  exercise  of  sound 
judgment  and  the  application  of  dependable  knowledge 
relating  to  the  various  problems  of  greenhouse  cropping. 
But  the  chief  motive  in  calling  attention  to  them  here  is 
to  emphasize  the  fact  that  the  most  intensive  cropping 
plans  must  be  employed  in  greenhouse  management  if 
maximum  profits  are  to  be  realized.  Certain  expenses 
are  constant,  regardless  of  whether  houses  are  handled 
poorly  or  skillfully.  The  interest  on  the  investment,  cost 
of  maintaining  the  buildings,  cost  of  fuel,  water,  manure, 
fertilizer,  tools,  labor,  etc.,  remain  fairly  constant. 

Now,  the  all  important  question  to  the  grower  is,  how 
can  he  make  every  foot  of  ground  yield  maximum  profits? 
All  of  the  problems  relating  to  the  production  of  various 
crops,  which  have  been  discussed  in  previous  chapters, 
should  have  the  most  careful  consideration.  But  atten- 
tion must  also  be  given  to  the  whole  matter  of  cropping 
plans.  What  crop  or  crops  should  be  grown?  Will  one 
vegetable,  grown  throughout  the  forcing  season,  pay  the 
largest  earnings,  or  will  it  be  more  profitable  to  grow  two 
or  more  different  classes  of  vegetables?  Should  the  crops 
follow  one  another  in  close  succession,  or  will  it  pay  best 
to  practice  companion  cropping?  These  are  some  of  the 
questions  which  will  be  discussed  in  this  chapter. 

Selection  of  crops. — A  number  of  factors  should  be 
taken  into  account  in  deciding  upon  the  crops  to  be 
grown.  Among  them  may  be  mentioned  the  following 
as  being  the  most  important : 

(1)  Demand.  There  is  always  a  great  demand  for  let- 
tuce, cucumbers  and  tomatoes,  although  prices  are  at 
times  low.  Generally  speaking,  it  is  best  to  grow  the 
vegetables  which  are  most  largely  consumed,  though 
there  are  many  exceptions.  It  is  possible,  sometimes,  to 
work  up  a  good  trade  for  a  special  crop,  as  witloof 


SYSTEMS   OF   CROPPING  381 

chicory,  for  example.    But  the  question  of  demand  should 
be  carefully  considered  before  planting  any  crop. 

(2)  Character  of  the  houses.    Low,  poorly  constructed 
houses  would  not  do  at  all  for  winter  cucumbers  or  to- 
matoes, while  they  might  give  at  least  fair  results  when 
planted  with  lettuce  or  radishes. 

(3)  Character  of  the  soil.     This  is  not  so  much  of  a 
factor  as  might  be  supposed,  unless  one  desires  to  grow 
head  lettuce,  when  the  soil  should  contain  a  large  per- 
centage of  sand.     Any  good   agricultural   soil   may  be 
made  to  yield  profitable  greenhouse  crops,  but  the  lighter 
types  are  preferred. 

(4)  Ease  with  which  the  crop  may  be  grown.     Some 
crops  are  much  more  difficult  to  grow  than  others.     It 
would  be  folly  for  an  inexperienced  grower  to  make  any 
attempt  to  produce  melons  under  glass.    As  experience  is 
gained,   the   more   difficult   crops  may   be   tried   and,   if 
desired,   they  may  be   grown  at  midwinter,   when  the 
greatest  skill  is  required. 

(5)  Labor  supply.     Some  crops  require  more  work 
than  others.    Winter  cucumbers  or  tomatoes,  for  instance, 
require  far  more  attention  than  lettuce. 

(6)  Personal  preference.     Farmers  succeed  best  with 
the  class  of  livestock  which  they  like  the  best,  and  grow- 
ers of  greenhouse  vegetables  obtain  the  best  results  from 
crops  which  appeal  to  them  the  most. 

Single  cropping. — It  is  unnecessary  to  enter  into  a 
lengthy  discussion  here  of  the  disadvantages  of  a  one- 
crop  system  of  farming,  whether  in  the  open  or  under 
glass.  It  is  never  economical  in  the  utilization  of  the 
applied  or  natural  sources  of  fertility,  and  fungous  and 
insect  pests  are  likely  to  be  much  more  destructive  than 
when  a  rotation  of  crops  is  followed.  When  one  crop  is 
grown  from  early  fall  until  August  15  of  the  following 
year,  advantage  cannot  be  taken  of  differences  in  light 
and  temperature  due  to  seasonal  changes.  Not  one  of  the 


382  VEGETABLE  FORCING 

* 

vegetables  is  adapted  to  culture  under  glass  throughout 
the  forcing  period.  This  factor  in  itself  is  a  strong 
argument  in  favor  of  growing  more  than  one  crop.  It  is 
not  unusual,  however,  to  find  a  grower,  operating  in  a 
comparatively  small  establishment,  growing  one  crop, 
often  tomatoes  or  cucumbers,  for  10  or  11  months  of  the 
year. 

Succession  cropping  is  popular  .with  a  majority  of 
American  greenhouse  growers.  At  least  90  per  cent  of 
them  believe  that  the  largest  profits  may  be  realized  by 
growing  either  two  or  three  crops.  Lettuce  is  the 
favorite  crop  during  the  late  fall  and  winter,  when  there 
is  so  much  dull,  cloudy  weather.  Tomatoes  and  cu- 
cumbers generally  do  well  early  in  the  fall,  but  they 
are  much  more  successful  in  the  spring  and  early  sum- 
mer. 

Succession  cropping  plans. — The  following  are  the 
most  important  succession  cropping  plans  for  the  entire 
forcing  season,  beginning  September  1  and  continuing 
until  August  15  of  the  next  year : 

(1)  Three  or  four  crops  of  lettuce  followed  by  cu- 
cumbers. 

(2)  Three  or  four  crops  of  lettuce  followed  by  tomatoes. 

(3)  One  crop  of  tomatoes  or  cucumbers,  one  or  two 
crops  of  lettuce  and  one  crop  of  tomatoes  or  cucumbers. 

Various  other  plans  of  succession  cropping  are  less 
common.  Among  them  may  be  mentioned  the  following: 
Lettuce,  cauliflower  and  tomatoes  or  cucumbers ;  cauli- 
flower, radish  and  tomatoes  or  cucumbers;  radish,  two 
crops  lettuce  and  tomatoes  or  cucumbers. 

The  cool  crops  of  minor  importance,  such  as  spinach, 
beet,  carrot,  cress,  mint,  swiss  chard,  etc.,  may  be  used  in 
the  rotation,  any  time  during  the  fall,  winter  and  early 
spring. 

Companion  cropping. — Companion  cropping  in  green- 
house culture  is  not  so  common,  although  used  to  a  con- 


SYSTEMS  OF  CROPPING  383 

siderable  extent.  The  fundamental  principles  involved 
are  practically  the  same  as  for  double  cropping  in  the 
open  ground,  but  attention  should  be  called  to  a  few  addi- 
tional factors,  as  follows : 

(1)  Land  values  under  glass  are  much  higher  than  out 
of  doors,  and  this  is  an  argument  for  intensifying  opera- 
tions by  intercropping. 

(2)  Steam  sterilization  destroys  weed  seeds  and  the 
soils  used  are  usually  light,  so  that  cultivation,  hoeing 
and  weeding  are  not  so  necessary,  and  close  planting, 
therefore,  is  less  objectionable  from  this  standpoint  than 
in  the  open  ground. 

(3)  A  higher  standard  of  quality  is  required  for  green- 
house  products,   and   companion   cropping   may  be   the 
means  of  lowering  the  quality,  as  when  radishes  and 
lettuce  are  crowded  and  shaded  by  larger  plants. 

(4)  Soil  adaptation  must  be  carefully  considered.     It 
is   a   mistake   to   attempt   to   grow   two   crops   together 
in  the  greenhouse  unless  both  are  well  adapted  to  the 
soil. 

(5)  The  question  of  temperature  is  the  most  important 
factor,  and  often  the  most  serious  handicap.    A  common 
practice  is  to  plant  cucumbers  in  beds  of  lettuce.     Al- 
though the  plan  is  successful  to  a  greater  or  lesser  extent, 
one  or  both  crops  usually  suffer  because  of  unsuitable 
temperatures.     This  condition  is  so  serious  in  the  opin- 
ion of  some  growers  that  they  never  attempt  to  grow 
crops  together  which  have  different  temperature  require- 
ments. 

(6)  The  manurial  requirements  of  each  crop  should  also 
receive   consideration.     This   problem,   however,   is   not 
serious,  because  a  soil  that  contains  sufficient  manure  to 
produce  a  good  crop  of  lettuce  will  also  be  satisfactory 
for  tomatoes  and  cucumbers. 

(7)  The  size  of  each  kind  of  plants  at  the  time  of  set- 
ting should  be  given  the  closest  attention.    For  example, 


384  VEGETABLE  FORCING 

small  tomato  plants  might  be  greatly  injured  by  setting 
in  beds  of  large  lettuce,  while  large  ones  would  be 
damaged  only  slightly. 

Ideas  and  planting  distances  for  greenhouse  companion 
cropping  are  so  variable  that  it  is  impossible  to  present 
definite  plans  which  are  standard  in  the  culture  of  crops 
under  glass.  It  is  hoped,  however,  that  the  following 
will  be  suggestive  to  those  who  are  interested  in  this 
subject: 

1.  Cauliflower  (C),  Lettuce  (L). 

C  10  in.        L  C  L  C  L  C 

10  in. 

L  L  L  L  L  L  L 

10  in. 


Large,  vigorous  plants  of  cauliflower  and  lettuce  set 
at  the  same  time.  The  lettuce  should  be  harvested  in 
about  five  weeks. 

2.  Same  as  No.  1,  except  rows  of  radishes  are  planted 
between  the  solid  rows  of  lettuce  and  the  rows  of  lettuce 
and  cauliflower.     Eleven  or  12-inch  spaces  instead  of  10 
inches  are  desirable. 

3,  Cauliflower  (C),  Radish  (R). 

C  20  in.  C  C  C 

Radish  

Radish  

Radish  

Radish  

C  C  C  C 


Cauliflower  plants  20  by  24  inches  apart.  Radish  rows 
4  inches  apart.  Less  space  may  be  allowed  for  cauli- 
flower if  desired.  Radish  seed  sown  in  drills  at  the  time 
the  cauliflower  is  planted.  The  radish  seed  is  sometimes 
sown  broadcast  instead  of  in  drills. 


SYSTEMS   OF   CROPPING  385 


4.  Tomatoes  (T),  Lettuce  (L). 

T  9  in.         L  T  L  T 

9  in. 


If  desired,  lettuce  may  be  planted  several  weeks  in  ad- 
vance of  tomatoes  and  the  plants  cut  and  sold  at  a  sacrifice 
when  the  tomatoes  must  be  set  in  the  permanent  beds. 
Planting  distances,  time  of  planting  and  size  of  plants 
vary  greatly  in  the  management  of  different  commercial 
establishments. 

5.  Cucumbers  (C),  Lettuce  (L). 

C  14  in.      C       C       C       C       C 
9  in. 

L  7  in.   L    L    L    L    L    L    L    L    L    L 

8  in. 

L       LLLLLLLLLL 


L       LLLLLLLLLL 

C  C        C        C        C        C 

It  is  an  advantage  to  plant  the  lettuce  several  weeks  in 
advance  of  the  cucumbers,  and  to  sell  the  small  plants 
and  replant  the  spaces  with  large  cucumber  plants.  In 
some  instances  growers  plant  small  cucumber  plants,  but 
small  plants  are  usually  injured  by  the  crowding  of  the 
lettuce. 


386  VEGETABLE   FORCING 


6.  Carnations  (C),  Tomatoes  (T). 

CT  10  in.  C  CT 

10  in. 


CT  C  CT  C 

This  plan  is  used  largely  at  Kennett  Square,  Pennsyl- 
vania. Tomatoes  are  planted  in  place  of  the  carnations 
whenever  the  carnations  indicate  rapid  decline  very  early 
in  the  spring.  The  remaining  plants  of  carnations  are 
permitted  to  remain  in  the  beds  until  the  tomatoes  need 
all  of  the  space  or  the  carnations  fail  to  yield  any  con- 
siderable return.  Sometimes  large  tomato  plants  are  set 
between  carnations  without  the  immediate  removal  of 
the  latter. 

7.  Fig.  48  shows  potted  cucumber  plants  being  grown 
between   gladioli   on   a   raised   bench.      Both    classes   of 
plants  were  thriving  when  the  photograph  was  taken. 

8.  Florists    sometimes    plant   tomatoes    or   cucumbers 
with  various  kinds  of  flowers,  whenever  the  latter  be- 
come exhausted  as  the  weather  becomes  warmer  in  the 
spring  or  early  summer.     For  example,   tomato  or  cu- 
cumber plants  may  be  set  between  rows  of  sweet  peas 
when  the  producing  period  of  the  latter  is  approaching 
an  end. 


CHAPTER  XXII 
FRAME  CROPS 

Frames  vs.  greenhouses. — It  is  generally  conceded  that 
greenhouses,  especially  in  northern  sections,  possess,  for 
the  forcing  of  most  vegetables,  distinct  advantages  over 
frames.  This  subject  was  discussed  more  fully  on 
page  13.  It  would  be  folly,  however,  to  take  the  stand 
that  there  is  no  place  for  the  use  of  frames  in  the  forcing 
of  vegetables,  for  this  is  far  from  the  truth.  Even  many 
of  our  most  successful  and  extensive  northern  greenhouse 
vegetable  growers  have  large  areas  of  frames.  They  are 
adapted  to  the  growing  of  certain  crops,  especially  the 
cool  ones,  such  as  lettuce,  radish,  cauliflower  and  other 
hardier  classes,  as,  for  instance,  the  dandelion.  They  find 
a  most  useful  place  in  the  operations  of  gardeners  living 
near  the  seashore,  particularly  southward,  where  the  ex- 
tremes of  temperature  are  not  so  great  as  in  farther  in- 
land northern  districts.  In  the  warmer  sections  of  the 
country,  some  crops,  as  head  lettuce,  thrive  much  better 
in  frames  than  in  superheated  greenhouses. 

Gardeners  with  limited  capital  can  engage  in  vegetable 
forcing  by  purchasing  only  a  few  sash.  As  the  profits 
increase,  additional  sash  may  be  obtained,  so  that  in  the 
course  of  a  few  years  an  important  enterprise  may  be 
established.  Frequently  the  sash  are  used  in  the  con- 
struction of  cheap  greenhouses,  and  in  these  greenhouses 
the  process  of  evolution  is  followed  by  large  modern 
ranges. 

Importance  of  frame  forcing. — Very  large  areas  in 
various  parts  of  the  country  are  devoted  to  frame  crops. 
The  most  extensive  plantings  are  in  North  Carolina, 
though  frames  are  used  on  a  large  scale  in  all  of  the  South 

387 


388 


VEGETABLE  FORCING 


Fig.    132. — Well-protected  wooden  coldframes. 

Atlantic  coast  states,  whence  shipments  are  made  in  car- 
load lots.  The  industry  has  attained  a  high  degree  of  per- 
fection near  Norfolk,  where  there  is  a  special  frame- 
growers'  association.  Thousands  of  sash  are  used  in 
Philadelphia  County,  Pa.  Rather  unusual  development 
of  frame  forcing  has  occurred  in  the  northern  part  of  New 
Jersey.  For  example,  there  are  about  150,000  sash  within 
an  area  of  one  square  mile  near  Richfield,  N.  J.  Market 
gardeners  and  truckers  throughout  the  country  employ 
hotbeds  and  coldframes  to  a  great  extent  for  the  forcing 
of  vegetables. 

Location  of  frames. — The  frames  should  be  located 
near  the  buildings  where  the  tools  and  supplies  are  kept. 
There  should  be  an  ample  supply  of  water  with  pipe  out- 
lets at  convenient  intervals.  Protection  of  some  kind,  as 
afforded  by  buildings,  board  fences,  hedges  or  woods,  is 
necessary.  Fig.  132  shows  an  ideal  arrangement,  the 
shed  nearby  being  convenient  for  the  storage  of  sash, 
manure,  sand  and  supplies. 

Construction  of  frames. — When  frames  are  used  on  a 
very  large  scale,  they  are  usually  portable  or  temporary. 
They  may  be  put  up  in  sections,  as  shown  in  Fig.  132, 
when  it  is  possible  to  remove  and  store  them  in  any 


FRAME   CROPS 


389 


convenient  way  until  wanted  again.  The  commoner 
method  is  to  use,  for  the  sides,  boards  which  are  nailed 
to  stakes,  as  shown  in  Fig.  133.  Between  seasons,  the 
boards  may  be  used  for  the  blanching  of  celery  if  desired. 
Most  of  the  extensive  frame  growers  do  not  use  cross 
bars  for  the  support  of  the  sash,  though  they  are  an  ad- 
vantage in  some  respects  and  a  disadvantage  in  others. 
It  is  largely  a  matter  of  preference. 

There  is  a  marked  tendency  to  use  concrete  in  the  con- 
struction of  frames.  The  walls  need  not  be  more  than 
3  inches  thick.  When  banked  on  the  outside  with  manure, 
they  are  practically  as  serviceable  in  protecting  the 
plants  from  cold  as  are  wood  side  boards.  Light  T-iron, 


Fig.   133. — An  extensive  flat  of  coldframes.     Note  method  of  ventilation   and  side- 
boards nailed  to  stakes. 

inverted,  may  be  used  for  cross  bars,  if  these  are  desired. 
The  durability  of  this  type  of  frame  appeals  to  growers 
who  have  found  the  frequent  renewal  of  wooden  frames 
an  expensive  proposition. 

Cloth-covered  frames. — In  North  Carolina,  South  Caro- 
lina and  other  southern  sections  where  the  climate  is  not 
severe,  the  frame  is  usually  covered  with  cloth  instead  of 


390  VEGETABLE  FORCING 

glass.    Beattie  gives,  in  Farmers'  Bulletin  460,  the  follow- 
ing description  of  a  typical  cloth-covered  frame : 

'The  covering  of  cheap,  unbleached  muslin  is  supported  on  strips 
of  wood  1  inch  thick  and  2^  or  3  inches  wide,  which  are  raised 
in  the  center  by  being  carried  over  the  top  of  a  stake ;  the  ends  are 
held  down  by  nailing  to  the  sides  of  the  bed.  The  lumber  for  the 
sides  is  usually  1  by  12  inches  by  16  feet  of  the  cheaper  grades  of 
cypress  or  a  good  grade  of  common  shortleaf  pine.  The  stakes  for 
holding  the  boards  in  place  are  1  by  3  or  2  by  3  inches  in  size,  and 
are  driven  about  1  foot  into  the  ground.  These  cloth-covered  beds 
are  usually  14  feet  in  width,  but  some  growers  prefer  them  10,  12 
or  20  feet  wide.  The  length  of  the  frames  varies  greatly,  but  the 
longer  ones  generally  run  from  90  to  100  yards,  depending  entirely 
upon  the  space  available  and  the  evenness  of  the  ground.  The 
frames  usually  run  east  and  west,  with  the  cloth  fastened  to  the 
north  edge  of  the  frame.  Most  of  these  frames  are  temporary  and 
are  taken  apart  and  stored  during  the  summer  months. 

"Before  placing  the  frames  in  position  in  the  autumn  the  soil  is 
plowed,  thoroughly  fitted,  and  given  a  liberal  dressing  of  well-rotted 
stable  manure  and  commercial  fertilizers.  The  placing  of  the  boards 
will  cause  some  trampling  of  the  bed,  and  before  putting  in  the 
ends  and  nailing  on  the  rafters  or  strips  to  support  the  cloth  it  is 
desirable  to  loosen  the  soil  again  by  means  of  a  harrow  or  cultivator. 
The  stakes  for  supporting  the  cross  strips  or  rafters  are  then  driven 
through  the  center  and  the  strips  nailed  in  place  at  intervals  of  4  feet. 
The  ends  are  inclosed  by  means  of  12-inch  boards,  and  the  bed  is 
then  ready  for  the  cloth  cover.  The  cloth  is  stitched,  with  the  strips 
running  lengthwise  of  the  bed,  into  one  great  sheet  large  enough 
to  cover  the  entire  bed.  This  sheet  is  fastened  on  the  north  side  of 
the  frame  by  nailing  over  it  plastering  laths  or  similar  strips  of 
wood.  The  cloth  should  not  be  fastened  to  the  top  edge  of  the 
board,  but  on  the  side  1  or  2  inches  below  the  top.  For  fastening 
the  sheet  on  the  south  side  of  the  frame  short  loops  of  string  or 
cloth  are  attached  to  its  edge,  and  these  are  looped  over  nails  driven 
into  the  side  of  the  bed.  In  some  cases  brass  eyelets,  such  as  are 
used  in  tent  flaps,  are  inserted  in  the  edge  of  the  cloth  and  hitched 
over  nails  or  pins.  Another  method  is  to  hem  the  cloth  on  one 
edge  and  run  a  ^-inch  rope  through  the  hem.  The  addition  of  the 
rope  makes  it  comparatively  easy  to  fasten  the  cloth  to  the  side  of 


392  VEGETABLE  FORCING 

the  bed  and  also  prevents  tearing  the  sheet  in  handling.  The  cost 
of  these  frames,  including  lumber  and  muslin,  together  with  the 
necessary  facilities  for  supporting  and  fastening  the  cloth,  will  be 
from  35  to  50  cents  a  running  foot  for  a  bed  14  feet  wide. 

"If  it  is  necessary  to  refit  the  land  while  the  frames  are  in  place, 
the  cloth  is  turned  back  into  the  alleys  between  the  frames,  the 
strips  that  support  the  cloth  are  removed,  and  a  1-horse  plow  is 
taken  into  the  inclosure.  After  the  land  is  plowed  and  thoroughly 
fitted,  the  strips  are  again  put  in  place.  As  the  work  of  cultivating 
the  crops  must  all  be  done  by  hand,  it  is  essential  that  the  soil  be 
well  prepared  before  planting." 

Sash-covered  frames. — Various  plans  are  followed  in 
the  North  for  the  making  of  sash-covered  frames. 
De  Baun  describes  the  following  plan,  which  is  used  at 
Richfield,  N.  J. : 

"The  soil  is  previously  prepared  by  being  leveled,  heavily  manured 
and  sometimes  plowed.  The  frames  are  usually  made  of  spruce 
boards,  16  feet  long,  1%  inches  thick  and  10  inches  wide.  They  are 
run  northeast  and  southwest  with  a  5-inch  pitch  toward  the  south- 
east, so  that  the  full  benefit  of  the  morning  sun  may  be  had.  Each 
frame  is  usually  made  25  sash  long  and  the  patch  between  the 
frames  is  usually  about  20  inches  wide.  The  frame  boards  are 
nailed  to  2  by  3  chestnut  stakes,  27/>  feet  long,  driven  into  the  soil 
on  the  outside  of  the  frames.  Bolts  an  inch  in  diameter  and  23 
inches  long,  provided  with  large  washers,  are  run  across  the  path 
to  hold  the  boards  securely  in  place.  The  paths  are  filled  with  coal 
ashes,  covering  the  rods  so  that  the  latter  cause  no  inconvenience 
to  the  workman  when  walking  in  the  alleys,  and  the  ashes  help  also 
to  keep  the  cold  out  of  the  frames  and  prevent  the  paths  from  be- 
coming muddy.  Frames  well  made  will  last  five  years." 

Frames  of  the  type  just  described  are  fairly  common 
in  the  North,  except  that  the  bolts  in  the  alleys  are  not 
generally  employed.  Standard  sash,  3  by  6  feet  in  size, 
are  used  by  most  growers.  Though  thousands  of  sash 
are  glazed  with  very  small  panes  of  glass,  it  is  desirable 
to  use  larger  sizes,  preferably  the  10  by  12  size.  If  the 
sash  are  painted  every  other  year,  kept  in  repair,  stored  or 
stacked  when  not  in  use,  they  will  last  15  to  20  years. 


FRAME   CROPS 


393 


Mats  and  shutters. — In  very  cold  weather,  sash  alone 
will  not  keep  frost  out  of  the  frames ;  additional  protec- 
tion, therefore,  is  necessary  at  times.  Probably  no  other 
covering  is  more  effective  in  guarding  against  cold  than 
rye  straw  mats  (Fig.  134),  though  the  sea  grass  mats, 
seen  in  Fig.  135,  are  most  excellent.  If  better  protection 
is  required,  board  shutters  placed  over  the  mats  and 
manure  banked  around  the  outside  of  the  frames  will 
take  care  of  the  plants  when  the  weather  is  very  cold. 
Growers  in  .the  coldest  parts  of  the  North,  who  use 
various  methods  of  heating  the  frames,  often  employ  mats 


Fig.    135. — Frame    cauliflower   following   a   companion    crop    of   lettuce.     Note  mats 
which  are  being  thoroughly  dried  before  they  are  stored  for  the  summer. 

and  occasionally  shutters  to  conserve  the  heat.  It  is  not 
uncommon  to  see  both  mats  and  shutters  on  steam-heated 
frames  during  the  daytime,  when  there  are  high  winds 
and  extremely  low  temperatures. 

Heating  frames. — It  is  impossible  to  give  any  rule  for 
the  heating  of  frames.  Thousands  of  frames  are  used 
without  any  artificial  heating.  In  the  South,  the  muslin 
or  sash-covered  frames  will  keep  the  plants  growing 
throughout  the  winter.  In  the  North,  they  may  give  the 
necessary  winter  protection  to  certain  crops,  and  rapid 


394  VEGETABLE  FORCING 

growth  is  not  expected  until  March  or  even  April,  when 
the  sun  furnishes  the  required  heat.  Crops  may  be  practi- 
cally matured  in  the  fall,  when  they  are  covered  with 
sash  merely  as  a  matter  of  protection  until  the  vegetables 
are  sold. 

Again,  sash  may  be  used  for  a  period  more  or  less 
definite  in  the  spring,  simply  to  advance  the  crops  until 
no  protection  of  any  kind  is  needed,  and  if  desired  both 
the  glass  and  the  frames  may  be  removed  and  all  of  the 
ground  devoted  to  the  crops.  This  plan  is  generally  used 
from  Norfolk  southward. 

In  the  colder  parts  of  the  country  it  is  often  an  ad- 
vantage to  heat  the  frames.  Ordinary  hotbeds  (Figs.  136 
and  137),  varying  in  depth  of  manure  from  a  foot  to  3 
feet,  are  in  common  use  for  a  great  variety  of  purposes. 
A  coil  or  two  of  steam  or  hot  water  pipes  are  often  placed 
in  frames,  and  this  plan  is  gaining  friends  every  year  over 
the  old  plan  of  heating  with  manure.  The  temperature  of 
the  frames  may  be  better  controlled  with  steam  than  with 
manure,  and  the  cost  of  heating  the  frames  is  often  less. 

Fertilizing. — The  principles  involved  in  the  feeding  of 
greenhouse  crops  (Chapters  IV  and  V)  are  the  same  as 


Fig.    136. — Surface  hotbed.      Note   notched  block   for  supporting   sash. 


FRAME  CROPS 


395 


for  the  growing  of  the  various  classes  of  vegetables  in 
coldframes.  In  many  instances  it  is  not  so  convenient  to 
apply  manures  and  fertilizers  in  frames  as  in  greenhouses, 
and  perhaps  greater  care  should  be  taken  to  have  the  soil 
fully  and  properly  enriched  before  the  crops  are  started. 

Watering. — All  that  was  said  in  Chapter  X  about 
watering  applies  to  the  moisture  problem  of  frame  crops. 
Success  or  failure  hinges  on  this  operation  more  than  on 
any  other  factor.  Evaporation  is  often  very  rapid,  and 
constant  alertness  is  required  in  order  that  the  plants  do 
not  suffer  at  any  time  from  an  insufficient  supply  of  soil 
moisture.  It  is  also  important  to  avoid  over-watering 
and  to  maintain  suitable  atmospheric  conditions  for  each 


Fig.   137. — Pit  or  hotbed,   showing  drainage  basin. 

crop.      The    overhead    system    of    irrigation    is    often 
employed  for  frame  crops. 

Ventilation. — Sash-covered  frames  may  be  ventilated 
in  various  ways.  When  there  are  cross  bars  the  sash  may 
be  shoved  either  way  so  as  to  give  as  much  ventilation  as 


396  VEGETABLE  FORCING 

may  be  necessary.  As  a  rule,  the  opening  is  made  on  the 
side  away  from  the  wind,  so  that  the  wind  will  not  blow 
into  the  frame.  If  only  a  small  amount  of  ventilation  is 
needed,  every  other  or  perhaps  every  third  or  fourth  sash, 
moved  only  an  inch  or  two,  will  admit  sufficient  air. 

When  there  are  no  cross  bars,  blocks  of  wood  may  be 
placed  under  the  ends  of  the  sash  or  at  some  distance 
from  the  ends  of  them,  as  shown  in  Fig.  138.  This  system 
is  somewhat  objectionable  on  account  of  its  tendency  to 
warp  the  sash.  In  warm,  sunny  weather  the  sash  may 
be  entirely  removed  during  the  day  and  replaced  on  the 
frames  in  the  evening.  A  careful  study  of  the  appearance 
of  the  plants  will  enable  the  gardener  to  determine 
whether  they  are  being  properly  ventilated. 

Cloth  covers  are  removed  from  the  frames  whenever 
the  weather  will  permit.  While  they  conserve  heat  they 
also  exclude  sunlight,  and  if  they  are  kept  on  too  much 
of  the  time  the  plants  will  become  weak  and  spindling 
and  subject  to  disease. 

Control  of  pests. — For  methods  of  controlling  various 
insect  and  fungous  enemies,  see  Chapters  VII  and  VIII, 
and  notes  on  different  classes  of  vegetables. 

VEGETABLES  GROWN  IN  FRAMES 
Asparagus  may  be  forced  at  any  time  during  the  winter 
in  heated  frames.  The  roots  from  which  the  shoots  are 
to  be  grown  are  dug  late  in  the  fall  and  stored  in  a  cool, 
moist  place  until  wanted  for  use.  The  details  of  culture 
are  essentially  the  same  as  when  the  crop  is  forced  in  the 
greenhouse.  See  Chapter  XII  for  particulars. 

Bean. — This  vegetable  is  sometimes  grown  in  frames 
as  a  spring  crop.  The  covering  of  cloth  or  glass  should 
be  used  for  about  a  month,  or  longer  in  the  coldest  sec- 
tions, and  then  no  further  protection  need  be  given.  An 
excellent  plan  is  to  plant  bush  beans  at  proper  intervals, 
in  rows  not  less  than  22  inches  apart,  between  rows  of 


398  VEGETABLE  FORCING 


Fig.  139. — A  coldframe  plat  near  Norfolk,  Va.     Note  method  of  ventilating. 

spring  lettuce  when  the"  latter  crop  is  well  advanced. 
After  the  lettuce  is  cut,  all  of  the  ground  is  devoted  to 
beans.  Any  of  the  bush  or  snap  varieties  may  be  used. 
The  wax-podded  type  is  generally  most  popular. 

Beans  as  a  commercial  frame  crop  do  not  offer  great 
possibilities,  though  it  is  much  better  to  grow  them  than 
to  have  the  frames  idle. 

Beet. — Though  the  beet  as  a  frame  crop  is  not  generally 
regarded  as  so  profitable  as  the  radish  and  lettuce,  it  is  a 
favorite  crop  with  some  growers.  It  is  usually  grown 
without  the  employment  of  artificial  heat.  Sometimes 
the  seed  is  sown  in  the  summer  and  the  crop  protected  in 
frames  until  Thanksgiving  or  later,  if  the  climate  is  not 
too  severe. 

At  Norfolk  it  is  a  common  practice  to  sow  from  De- 
cember 15  to  January  15,  and  to  protect  the  plants  with 
glass  until  about  April  1,  when  the  sash  are  transferred 
to  cucumber  frames.  The  seedlings  may  be  started  in 
separate  beds  and  transplanted  into  the  frames.  The 
early  maturing  varieties,  such  as  Early  Egyptian  and 
Early  Model,  are  employed  for  forcing.  See  page  359 
for  additional  notes. 


FRAME  CROPS 


399 


Carrot. — The  carrot  is  extensively  grown  in  frames. 
The  small,  early  maturing  varieties  are  employed.  They 
may  be  grown  as  a  fall  crop  or  all  winter  if  the  climate  is 
not  too  severe,  but  the  greatest  profits  are  generally 
derived  from  spring  sowings.  In  the  Richfield,  N.  J., 
section,  seed  is  sown  in  the  frames  about  August  1. 
Nantes  is  the  most  popular  variety  in  this  section  on 


Fig.    140. — Frame  crop   of  Nantes  carrot. 

account  of  its  good  color,  thriftiness  in  growth,  sweet 
flavor  and  its  certainty  in  producing  good  roots. 

The  fall  frame  carrots  are  usually  planted  in  double 
rows  only  an  inch  apart,  with  10-inch  spaces  between  the 
pairs  of  rows.  This  method  of  planting  is  said  to  allow 
ample  soil  space  for  the  development  of  good  roots,  and  it 
insures  the  free  circulation  of  air  among  the  tops.  Sash 
are  placed  on  the  frames  in  November  and  the  carrots 
will  be  ready  to  bunch  for  the  holiday  trade.  Fig.  140 
shows  a  spring  crop  of  carrots,  the  seed  of  which  was 
sown  March  1  between  rows  of  lettuce. 

Cauliflower  (Fig.  141)  is  grown  to  a  considerable  extent 
in  frames  on  Long  Island.  The  principles  involved  are 
the  same  as  when  the  crop  is  grown  in  greenhouses.  It 


400 


VEGETABLE  FORCING 


^PMMoHp 


4. 


m^ 
•  *  i*M&. 

mwmm    ' 


.«*»*• 


^  cc  ^'«  ?'•';-  >'-;.  '-••; '  '*•'•  t---?-^ :'<i'"'~'1*'f"**  ^- 

'^,*.-^:s>*  ' 


Fig.  141. — Frame  cauliflower  ready  to  head. 

may  be  grown  both  as  a  fall  and  as  a  spring  crop.  See 
Chapter  XV  for  data  on  the  forcing  of  this  crop. 

Celery  is  grown  occasionally  as  a  spring  frame  crop. 
The  plants  should  be  started  as  explained  in  Chapter  IX 
and  transferred  to  the  frames,  when  there  will  be  no  un- 
certainty about  the  possibilities  of  maintaining  proper 
temperatures.  All  the  notes  on  celery  as  a  greenhouse 
crop,  page  362,  apply  equally  well  to  its  culture  in  frames. 
It  .is  possible  to  mature  the  crop  six  weeks  earlier  in 
frames  than  in  the  open  ground. 

Chinese  cabbage  may  be  grown  in  frames  as  a  spring 
crop  with  entire  success,  provided  careful  attention  is 
given  to  watering,  ventilation  and  the  removal  of  the  sash 
when  the  temperature  becomes  very  high.  See  page  360 
for  additional  notes. 

Corn  salad,  when  given  careful  attention,  is  a  profitable 
frame  crop.  It  is  sown  in  rows  about  8  inches  apart. 
Free  ventilation  and  skillful  watering  are  required  to 
prevent  the  ravages  of  damping-off  fungi. 

Cress  may  be  grown  in  frames  in  the  same  manner  as 
that  explained  for  greenhouse  culture,  page  361. 

Cucumber  (Fig.  142). — The  cucumber  is  one  of  our 


FRAME  CROPS 


401 


most  important  spring  frame  crops.  In  the  Norfolk 
region,  thousands  of  sash  are  devoted  to  this  vegetable. 
The  seed  is  sown  in  greenhouses  or  hotbeds  about 
March  1,  and  as  soon  as  the  plants  are  up  they  are  trans- 
planted into  veneer  boxes  6  by  6  by  6  inches  in  size.  Five 
or  six  plants  are  set  in  each  box  and  the  plants  are  finally 
thinned  to  three  or  four.  About  April  1,  one  box  or  hill 


Fig.   142. — Frame  cucumbers  near  Norfolk. 

of  plants  is  set  under  each  3  by  6-foot  sash,  and  from 
May  15  to  20  the  sash  and  frames  are  removed. 

The  cucumber  plants  are  set  in  every  other  frame, 
and  when  they  need  no  further  protection,  May  15 
to  20,  the  alternate  beds  of  beets  are  ready  to  market; 
the  cucumber  vines  are  then  trained  over  ground 
occupied  by  beets  only  a  few  days  before.  Stable  manure 
is  used  in  liberal  amounts  and  supplemented  by  complete 
fertilizer.  Top-dressings  of  fertilizer  are  also  employed 
if  additional  growth  is  desired.  When  the  frames  are 
removed,  the  ground  between  them  is  thoroughly  culti- 
vated and  the  cucumber  vines  are  turned  up,  the  soil 
cultivated  and  usually  top-dressed  with  fertilizer,  and  the 
vines  replaced.  Spraying  is  also  practiced. 


402 


VEGETABLE  FORCING 


In  New  England  and  other  northern  districts  the 
plants  are  generally  started  in  pots  in  greenhouses  or  hot- 
beds, and  transferred  to  coldframes  late  in  the  spring, 
when  the  sash  alone  will  give  all  the  protection  that  is 
needed.  This  method  will  produce  a  crop  of  cucumbers 
four  to  six  weeks  earlier  than  is  possible  by  planting  seed 
in  the  open  ground.  See  Chapter  XVIII  for  complete 
notes  on  forcing  cucumbers. 

Dandelion  may  be  forced  from  seed  sown  in  the  frames 
or  from  crowns  which  have  been  grown  in  the  open  and 


Fig.  143. — Soil  in  coldframe,  after  sowing  seed  of  dandelion,  carrot,  parsley, 
etc.,  for  the  fall  crop,  is  covered  with  salt  hay  to  conserve  moisture  and  to  prevent 
the  soil  from  baking.  When  seedlings  are  up,  the  hay  is  removed. 

transferred  to  the  frames.  (See  page  364.)  Seed  should 
be  sown  about  July  1.  Sash  may  be  placed  over  the 
frame  at  any  time  during  the  winter,  and  if  a  little  heat 
is  provided  the  plants  can  be  forced  to  marketable  size  in 
three  or  four  weeks.  If  desired,  the  frames  may  be  left 
uncovered  until  March,  when  the  sash  alone,  without 
any  artificial  heat,  will  force  a  satisfactory  growth. 
The  demand  for  dandelion  is  increasing,  and  with 


FRAME   CROPS 


403 


good    management    it    makes    a    profitable    frame    crop. 

Eggplant. — The  eggplant  is  grown  to  some  extent  as 
a  frame  crop.  A  good  hotbed  or  warm  greenhouse  is 
required  to  start  the  plants.  They  should  be  first  trans- 
planted into  small  pots,  and  shifted  until  they  are  in  4  or 
5-inch  pots,  and  thence  to  the  frames.  After  the  season 
is  well  advanced  and  there  is  no  danger  of  chilling  the 
plants,  the  sash  may  be  removed.  See  page  365  for  addi- 
tional notes. 

Kohl-rabi. — Kohl-rabi  is  easily  grown  as  a  spring  frame 
crop.  The  most  economical  use  of  the  ground  will  be 


Fig.  144. — Coldframes  ready  for  seeding  in  August  with  carrots  and  other  fall  crops. 

obtained  if  the  plants  are  started  in  beds  and  then  trans- 
planted into  frames.     (See  page  366.) 

Lettuce  (Fig.  139)  is  unquestionably  the  most  im- 
portant frame  crop.  It  is  extensively  grown  in  frames  in 
all  parts  of  the  country.  As  a  hotbed  crop  it  has  been 
grown  from  the  earliest  days  of  vegetable  forcing  in  the 
United  States.  As  a  frame  crop  in  the  South,  whether 
the  frames  are  covered  with  sash  or  muslin,  it  receives 
much  more  attention  than  any  other  crop.  In  the  North 


404 


VEGETABLE  FORCING 


hundreds  of  frames  in  which  lettuce  is  grown  are  heated 
by  steam  or  hot  water. 

Big  Boston  is  the  main  forcing  variety,  especially  in 
the  Atlantic  coast  states.  It  is  extremely  hardy  and  will 
stand  a  large  amount  of  exposure  without  serious  injury. 
All  of  the  varieties  mentioned  on  page  207  are  also  grown 
to  some  extent  in  frames. 

Seed  for  the  fall  crop  is  generally  sown  from  August  15 
to  20.  If  the  plants  for  the  spring  crop  are  to  be  wintered 
in  the  frames,  the  seed  should  be  sown  about  October  1 
in  the  South,  and  the  plants  set  in  the  frames  later  in  the 
fall  and  covered  with  sash  or  muslin.  In  the  North  the 


Fig.   145. — Choice  heads   of  lettuce   saved   for  the  production   of  seed. 

plants  may  be  wintered  in  the  frames  or  started  in  hot- 
beds or  greenhouses  in  January  or  February,  and  then 
set  in  the  frames  in  March,  or  even  as  late  as  April  1. 
The  date  of  sowing  and  transplanting  may  depend  largely 
on  the  uses  of  the  sash  and  frames  for  other  crops.  Big 
Boston  is  set  at  various  distances,  probably  9  by  10  inches 
apart  being  the  average. 

Muskmelons  may  be  grown  in  frames  by  the  same 


FRAME  CROPS 


405 


methods  as  were  explained  for  cucumbers  (page  400). 
General  questions  relating  to  the  forcing  of  muskmelons 
are  discussed  in  Chapter  XIX. 

Mustard  is  easily  forced  in  frames.  See  page  367  for 
directions. 

Onion. — Onion  sets  may  be  forced  in  frames  by  the 
employment  of  methods  described  on  page  367. 

Parsley  is  easily  forced  in  frames  by  the  use  of  methods 
described  on  page  369  for  growing  it  in  greenhouses.  It 
is  a  profitable  crop  wherever  good  markets  are  available. 

Pepper. — The  pepper  is  a  satisfactory  spring  crop  for 
frame  culture.  It  pays  well  unless  southern  competition 
is  too  severe.  The  plants  are  started  in  pots  and  trans- 
ferred to  the  frames  whenever  it  is  possible  to  maintain 
proper  temperatures.  See  page  370  for  notes  on  culture. 

Radish. — The  radish  is  one  of  the  most  profitable  and 
satisfactory  frame  crops.  It  is  easily  grown  and  gives 
quick  returns.  As  a  companion  crop  with  lettuce  and 


Fig.    146. —  Double   frames  are  sometimes  used  for  forcing  purposes. 


406  VEGETABLE  FORCING 

cauliflower,  it  has  no  equal.  See  Chapter  XVI  for  cul- 
tural notes. 

Rhubarb  may  be  forced  with  success  in  frames  heated 
by  manure  or  steam.  If  the  roots  are  not  planted  until 
early  spring,  no  artificial  system  of  heating  will  be  re- 
quired. On  account  of  the  length  of  the  leaf  stalks,  it  is 
necessary  to  use  frames  deeper  than  those  which  will  do 
for  lettuce  and  other  plants  that  do  not  attain  a  height  of 
more  than  10  inches.  For  cultural  details,  see  Chapter 
XIII. 

Spinach  is  easily  grown  in  frames  without  any  artificial 
heat.  A  fall  crop  may  be  harvested,  and  early  spring 
cuttings  may  be  made  of  plants  started  in  the  fall,  or 
perhaps  from  January  or  February  sowings,  depending 
upon  the  severity  of  the  climate.  With  proper  attention 
spinach  will  yield  about  as  large  returns  as  lettuce,  and  it 
may  be  the  means  of  avoiding  a  market  glut  of  lettuce. 
(See  page  372.) 

Swiss  chard  may  be  sown  in  January  in  frames,  or 
started  in  hotbeds  or  greenhouses  and  transplanted  into 
the  frames.  In  the  milder  sections  of  the  country,  pick- 
ings may  be  made  from  frames  throughout  the  winter. 

Turnip. — The  early  varieties  of  turnips  are  sometimes 
grown  in  coldframes,  though  this  crop  does  not  offer 
special  financial  inducements  as  a  forcing  proposition. 
(See  page  373.) 

Witloof  chicory  or  French  endive  claims  attention  as  a 
frame  forcing  crop.  For  further  paticulars  see  page  373. 


CHAPTER  XXIII 

MUSHROOMS 

Hundreds  of  greenhouse  vegetable  growers  are  in- 
terested in  the  culture  of  mushrooms,  and  this  volume 
would  not  fulfill  its  mission  without  a  brief  discussion  of 
the  most  important  phases  of  the  subject. 

Importance. — The  gardeners  of  all  civilized  countries 
have  long  been  interested  in  the  growing  of  mushrooms. 
In  England  and  France  the  industry  has  been  of  large 
commercial  importance  for  over  a  hundred  years.  Exten- 
sive areas  are  also  devoted  to  the  crop  in  Germany, 
Belgium,  Italy  and  other  European  countries. 

In  the  United  States  the  business  did  not  assume  large 
proportions  until  about  1900.  The  production  of  pure 
spawn,  which  has  made  the  growing  of  this  edible  fungus 
a  much  more  certain  financial  venture,  has  stimulated  the 
enterprise  until  special  sections  of  the  country  have  at- 
tracted much  attention  for  the  magnitude  of  the  mush- 
room business.  The  Kennett  Square  region  of  Penn- 
sylvania is  particularly  famous,  though  large  plantings 
are  made  near  all  of  our  great  centers  of  population. 
Individual  growers  may  have  two  acres  or  more  of  bed 
space  devoted  to  the  growing  of  mushrooms.  Duggar 
estimates  that  about  5,000,000  pounds  were  sold  during 
the  season  of  1913  and  1914. 

Most  of  the  crop  is  generally  sold  locally,  though  there 
is  an  increasing  tendency  to  develop  a  trade  with  distant 
points.  Practically  all  the  mushrooms  grown  in  the 
United  States  are  sold  in  the  fresh  state.  Large  quanti- 
ties of  the  canned  product  have  been  imported  from 
Europe,  particularly  France,  and  a  limited  supply  has 
been  dried  for  commercial  purposes,  the  latter  being 
used  mainly  for  flavoring  and  for  gravies. 

407 


408  VEGETABLE  FORCING 


Fig.  147. — Wooden  mushroom  houses  at   Kennett  Square,  Pa. 

Botanical  characteristics. — The  cultivated  mushroom 
so  familiar  to  growers  in  the  United  States  is  botanically 
known  as  Agaricus  campcstris.  It  consists  of  a  stalk  or 
stipe,  varying  in  height  from  2  to  5  inches,  and  in 
diameter  from  l/2  inch  to  1  inch.  The  top  or  expanded 
part  of  the  mushroom  is  known  as  the  "cap"  or  "pileus" ; 
this  varies  greatly  in  thickness  and  diameter,  according 
to  variety,  stage  of  growth  and  condition  under  which  it 
is  grown.  Varietal  variations  are  rather  marked,  the  caps 
of  some  being  whitish,  while  others  are  creamy  white  or 
perhaps  brown.  The  leaflike  or  gill-like  projections  on 
the  under  side  of  the  cap  are  termed  gills  or  "lamellae'' ; 
these,  for  a  time,  are  pink  in  color  in  the  white  or  cream- 
colored  species,  but  they  subsequently  turn  brown  or 
brownish  black.  The  dark-colored  spores  are  borne  on 
the  gills,  and  they  serve  as  the  reproductive  bodies  of  the 
mushroom. 

Spores  are  the  normal  propagative  bodies  of  this  fungus, 
but  growers  do  not  use  them  directly  in  the  production  of 
mushrooms,  although  under  favorable  conditions  they 
will  germinate  and  ultimately  produce  a  threadlike 
growth  termed  the  "mycelium." 

Where  to  grow  mushrooms. — The  most  extensive 
mushroom  plantations  in  the  world  are  in  France.  The 
city  of  Paris,  built  of  stones  largely  taken  from  quarries 


MUSHROOMS  409 

under  its  streets  and  properties,  is  the  center  of  this  great 
mushroom  industry.  Subterranean  quarries  near  the  city 
contain  immense  plantings,  thousands  of  beds.  In  fact, 
the  quarries  are  responsible  for  the  tremendous  develop- 
ment of  this  enterprise  in  France.  The  underground 
chambers  are  extremely  variable  in  shape  and  dimen- 
sions. They  may  be  5  to  20  feet  or  more  in  height  and 
width,  and  they  may  have  entrances  which  are  easily 
accessible,  or  it  may  be  necessary  to  provide  narrow 
openings  above  the  quarries,  with  windlasses  for  the 


Fig.   148. — A  modern  commercial  mushroom  range  at  Kennett  Square,   Pa.     Built  of 
concrete    and   tile.      Frostproof    and    fireproof. 

handling  of  manure  and  other  materials.  Ventilation  is 
provided  by  means  of  special  openings  or  ventilating 
devices  of  various  descriptions. 

In  England,  caves,  cellars  and  specially  constructed 
houses  are  employed.  In  the  United  States,  the  bulk  of 
the  commercial  crop  is  grown  in  special  houses  such  as 
are  shown  in  Figs.  147,  148  and  149.  The  majority  of 
the  American  mushroom  houses  are  cheap,  wooden  struc- 
tures, but  in  recent  years  more  expensive  buildings  have 
been  erected  by  experienced  growers.  Wood  is  unques- 
tionably the  most  common  material  used  in  the  construc- 
tion of  American  mushroom  houses,  although  many 
growers  are  employing  the  more  durable  materials,  such 
as  tile,  brick  and  concrete,  with  air  chambers  in  the  walls. 
In  most  instances  the  houses  are  comparatively  narrow, 


410 


VEGETABLE  FORCING 


Fig.   149. — A  New  Jersey   double  duty  house.      Mushrooms  are  grown   in  the  cellar 
and  plants  and  flowers  in  the  greenhouse  above. 

12  to  20  feet,  but  many  of  the  modern  ones  are  of  much 
greater  width,  and  they  may  be  hundreds  of  feet  in  length. 

The  most  economical  use  of  the  space  is  to  construct 
tiers  of  beds.  The  old  houses  seldom  contained  more 
than  two  or  three  beds,  while  some  of  the  new  ones  have 
as  many  as  five  beds.  Most  growers  prefer  single  beds  of 
about  3  feet  or  double  ones  of  6  or  7  feet  in  width.  (See 
Fig.  150.)  The  alleys  should  be  at  least  2  feet  wide,  and 
many  of  them  allow  more  space,  for  the  convenient 
handling  of  manure  and  other  material.  When  the  tiers 
contain  several  beds,  each  8  to  10  inches  deep,  provision 
must  be  made  for  strong  supports;  2  by  4  and  2  by  6 
scantling  are  generally  employed,  or  heavy  gas  pipe 
makes  a  stronger,  more  durable  and  more  sanitary  frame, 
and  the  boards  are  easily  removed  at  any  time  the  beds 
are  not  in  use. 

Mushrooms  are  grown  in  a  few  large  caves  in  America. 
Pits,  small  caves,  cellars  and  barns  are  often  used  by 
amateur  growers.  Florists  and  sometimes  vegetable 
gardeners  grow  mushrooms  under  greenhouse  benches. 
In  fact,  any  place  can  be  used  which  provides  proper 
cultural  conditions,  with  special  reference  to  heat  and 
moisture.  There  must  be  perfect  drainage  and  the  tern- 


MUSHROOMS 


411 


perature  requirements  are  rather  exacting.  Special 
piping  is  necessary  in  mushroom  houses  in  order  to  main- 
tain sufficient  heat. 

Material  for  beds. — Various  kinds  of  organic  materials 
have  been  used 
for  the  growing 
of  mushrooms, 
but  there  seems 
to  be  a  consen- 
sus of  opinion 
that  fresh  horse 
manure  gives 
the  best  results. 
Most  growers 
prefer  that  it 
contain  consid- 
erable straw,  al- 
though good  re- 
sults are  some- 
times obtained 
from  manure 
with  a  small 
proportion  of 
bedding.  If  saw- 
dust or  shav- 
ings have  been 
used  for  litter,  more  time  will  be  required  to  effect  proper 
fermentation,  and  it  is  likely  that  such  manure  does  not  give 
as  uniformly  good  results  as  strawy  manure.  The  French 
growers  prefer  manure  from  grain-fed  animals  bedded 
with  rye  straw.  Any  of  the  cereals  grown  in  America 
used  for  bedding  grain-fed  animals  will  produce  manure 
which  is  entirely  satisfactory  for  the  growing  of  mush- 
rooms. It  is  desirable  that  the  manure  be  fairly  open 
and  porous  after  it  has  fermented,  and  the  cereal  straws 
seem  to  bring  about  this  condition.  The  large  commer- 


Fig.  150. — Mushroom  beds  in  a  modern  house. 


412  VEGETABLE  FORCING 

cial  growers  buy  the  usual  supplies  of  city  stable  manure, 
which  is  often  shipped  in  carlots. 

In  many  instances  the  manure  is  placed  in  large  piles 
out  of  doors,  as  shown  in  Fig.  151,  and  allowed  to  fer- 
ment. There  are  advantages  in  keeping  the  manure 
under  cover  where  there  will  be  no  loss  from  leaching 
and  where  it  will  not  dry  out  rapidly,  but  the  objections 
to  open  air  composting  are  not  serious. 

Certain  essential  chemical  changes  occur  during  the 
process  of  fermentation,  which  also  materially  alter  the 
physical  properties  of  the  manure.  Fire-fanging  should 
be  avoided  as  much  as  possible.  To  encourage  the  proper 
kind  of  fermentation  it  is  necessary  to  keep  the  pile 
uniformly  moist  and  fairly .  compact.  The  supply  of 
moisture  in  the  compost  should  be  watched  carefully 


Fig.   151. — Composting  manure  for  the  growing  of  mushrooms. 

from  day  to  day.  Copious  applications  of  water  or  suffi- 
cient amounts  to  soak  the  manure  are  necessary  when  it 
is  placed  in  piles,  and  the  latter  should  not  be  more  than 
4  or  5  feet  deep.  It  is  generally  customary  to  turn  or 
fork  over  the  piles  from  two  to  four  times  during  the 
process  of  fermentation,  which  lasts  about  four  weeks. 
This  operation  is  essential  in  order  to  secure  uniform 
fermentation  throughout  the  compost  and  to  make  the 
manure  shorter  or  finer  in  texture.  Water  should  be 
added  whenever  necessary  while  the  manure  is  being 


MUSHROOMS  413 

forked  ov^r,  in  order  to  keep  all  parts  of  the  pile  equally 
moist.  Manure  hauled  from  the  cars  nearly  always  re- 
quires a  large  amount  of  water  when  it  is  placed  in  a  pile. 
The  temperature  will  rise  to  possibly  150  degrees,  but  in 
three  to  four  weeks  it  should  drop  to  about  130  degrees, 
and  if  the  manure  has  lost  its  unpleasant  odors,  and  the 
straw  has  become  dark  brown  in  color,  and  the  material 
friable  and  containing  the  right  amount  of  moisture,  the 
beds  may  be  filled.  Four  large  wagonloads  of  manure 
will  generally  be  sufficient  for  1,000  square  feet  of  beds. 

Preparation  of  beds. — As  stated  in  the  previous  para- 
graph, the  manure  may  be  placed  in  the  beds  after  the 
temperature  has  receded  to  about  130  degrees.  If  the 
beds  are  to  be  made  on  the  ground,  there  should  be  no 
uncertainty  about  them  being  perfectly  drained. 

Practically  all  American  growers  prefer  to  make  flat 
beds  rather  than  ridged  ones.  Flat  beds  are  the  simplest 
to  make,  and  they  are  more  economical  of  space  where 
tiers  of  beds  are  constructed.  Ridged  beds  are  about  2 
feet  wide  at  the  base,  they  taper  gradually  to  the  top  and 
are  12  to  15  inches  high.  They  are  generally  arranged  in 
groups  of  twos  with  approximately  12-inch  alleys  be- 
tween each  pair  of  beds.  This  plan  is  followed  in  the 
French  caves,  where  it  possesses  distinct  advantages, 
especially  in  providing  a  larger  total  area  of  bed  surface 
when  all  of  the  beds  are  made  on  the  ground.  This 
system  is  sometimes  seen  in  low  commercial  houses  of 
America,  or  in  private  cellars  and  pits. 

When  flat  beds  are  made  in  cellars  or  caves,  some 
growers  prefer  a  total  depth  of  12  to  14  inches,  several 
inches  or  perhaps  the  lower  half  of  this  depth  being  com- 
posed of  fresh,  hot  manure  and  the  upper  half  of  specially 
composted  manure.  The  hot  manure  furnishes  some  heat 
after  the  beds  have  been  planted  or  spawned,  and  this  is 
thought  to  be  of  value  in  locations  which  are  not  ade- 
quately heated.  Growers  operating  large  commercial 


414  VEGETABLE  FORCING 

houses  make  beds  10  to  12  inches  deep  sometimes,  but  this 
is  of  doubtful  expediency.  The  more  generally  approved 
plan  is  to  use  only  the  specially  composted  manure,  mak- 
ing beds  with  a  total  depth  of  8  to  10  inches,  after  the 
manure  has  been  firmed  or  compressed  by  the  use  of  a 
board  or  other  convenient  device.  A  certain  amount  of 
compacting  of  the  manure  is  necessary  to  prevent  it  from 
becoming  too  loose  and  dry. 

After  the  beds  have  been  filled,  the  temperature  of  the 
manure  may  rise  for  a  few  days  and  then  it  will  begin  to 
decline,  but  there  should  be  no  spawning  until  it  is  down 
to  75  degrees  or  preferably  70  degrees.  The  moisture  of 
the  beds  between  filling  and  spawning  should  also  be 
carefully  watched.  If  the  manure  has  been  properly  pre- 
pared and  the  beds  and  houses  are  well  constructed, 
there  should  be  very  little  trouble  in  this  connection. 
However,  light  sprinkling  is  sometimes  necessary  in 
order  to  maintain  proper  moisture  conditions.  A  practi- 
cal test  is  to  squeeze  the  compost  in  the  hand  at  the  time 
the  beds  are  filled.  If  no  drops  of  water  are  squeezed  out 
and  the  hand  remains  distinctly  moist,  additional  water 
is  not  required.  But  too  much  emphasis  cannot  be  placed 
upon  the  importance  of  having  perfect  moisture  condi- 
tions when  the  beds  are  filled.  Skillful  growers  never 
water  the  manure  in  the  beds. 

Spawn. — Success  in  growing  mushrooms  depends  very 
largely  upon  the  use  of  good  spawn.  English  spawn  was 
used  almost  exclusively  in  this  country  until  a  few  years 
ago,  and  although  it  was  regarded  as  the  best,  results 
from  its  use  were  very  uncertain.  Great  credit  is  due 
Duggar  for  his  work  in  developing  pure  culture  spawns 
which  have  placed  the  whole  proposition  on  a  more  cer- 
tain, scientific  and  satisfactory  basis,  thus  making  it  com- 
parable to  other  lines  of  horticultural  production. 

The  making  of  pure  culture  spawn  is  in  itself  a  special 
enterprise  requiring  skill  and  laboratory  equipment,  and 


MUSHROOMS  415 

it  is  not  feasible  or  practicable  for  every  grower  to  pro- 
duce his  own  spawn.  Those  who  are  interested  in  this 
phase  of  the  industry  should  study  Duggar's  "Mushroom 
Growing,"  Chapter  VIII.  It  is  gratifying,  however,  that 
there  are  reliable  American  firms  from  whom  pure  cul- 
ture spawn  may  be  obtained  at  reasonable  prices,  so  that 
no  one  need  take  chances  in  planting  ordinary  commercial 
spawn,  whether  it  is  made  in  the  United  States  or  in 
foreign  countries.  Growers  will  do  well  to  make  a 
thorough  investigation  of  the  sources  of  good  spawn 
before  making  purchases.  Different  varieties  may  be 
obtained  and  tested  just  as  gardeners  test  different  sorts 
of  tomatoes  or  lettuce. 

The  pure   cultures   are   generally   sold   in   the    usual 
commercial  brick  forms,  as  seen  in  Fig.  152.    The  bricks 


Fig.   152. — Drying  bricks  of  mushroom  spawn. 

measure  about  5^2  by  8y2  by  \y2  inches.  They  pack 
readily  for  shipment  and  are  easily  broken  for  spawning 
the  beds.  It  is  exceedingly  important  to  use  fresh  spawn. 
That  which  is  a  year  old  seldom  gives  good  results. 
Duggar  recommends  that  growers  use  spawn  not  more 
than  six  or  eight  months  old,  and  they  will  do  well  to 


416  VEGETABLE  FORCING 

make  arrangements  with  manufacturers  several  months 
in  advance  of  the  date  when  it  will  be  wanted  for  plant- 
ing. But  it  is  safer  to  have  delivery  arranged  for  only  a 
few  weeks  before  the  beds  are  spawned  in  order  to  avoid 
storage  risks. 

Spawning  the  beds. — As  previously  stated,  a  tempera- 
ture of  about  70  degrees,  which  may  be  determined  by  a 
thermometer  plunged  into  the  manure,  is  probably  best 
for  the  spawning  of  the  beds,  though  this  is  often  done  at 
temperatures  ranging  from  10  to  15  degrees  higher.  The 
beds  may  be  spawned  at  55  to  60  degrees,  but  the  mush- 
rooms will  grow  much  less  rapidly  if  the  spawning  is 
done  at  lower  temperatures  than  55  degrees. 

There  are  no  rules  regarding  the  best  distances  for  in- 
serting the  spawn.  Ordinarily,  a  brick  is  broken  into  10 
or  12  pieces,  sometimes  more,  and  one  piece  is  considered 
sufficient  for  about  a  square  foot  of  bed.  The  pieces  may 
be  planted  in  check  rows  a  foot  apart,  or  at  closer  inter- 
vals if  desired.  A  little  manure  is  raised  and  a  hole  made 
where  each  piece  of  spawn  is  to  be  inserted ;  the  spawn 
is  covered  with  an  inch  or  two  of  the  manure  and  pressed 
firmly  with  the  hand.  If  the  bed  seems  too  loose  after 
the  work  of  spawning  has  been  completed,  the  entire 
area  may  be  firmed  with  a  board  or  a  block  of  wood. 

Casing  the  beds. — Mushroom  beds  are  always  covered 
with  an  inch  or  two  of  fine,  rich,  moist,  loamy  soil  and 
this  operation  is  termed  "casing."  Its  purpose  is  to  con- 
serve moisture,  give  support  to  the  mushrooms  and  pre- 
sumably to  improve  the  quality  of  the  product.  The 
casing  is  usually  placed  on  the  beds  in  10  days  to  two 
weeks  from  the  date  of  spawning.  If  conditions  have 
been  right,  the  mycelium  will  then  appear  as  a  moldy 
growth  on  the  pieces  of  spawn.  It  is  an  interesting  fea- 
ture of  mycelium  growth  that  as  it  runs  through  the 
manure,  the  casing  acts  as  a  check  on  vegetative  develop- 
ment, thus  forcing  the  reproductive  development,  and  to 


MUSHROOMS  417 

case  too  soon  is  a  disadvantage.     During  the  intervals 
some  sprinkling  may  be  necessary  to  keep  the  beds  moist. 

Moisture  conditions. — Proper  moisture  conditions  at 
all  times  after  the  beds  have  been  started  are  of  the 
greatest  importance.  Excessive  humidity  in  the  house 
should  be  avoided,  but  the  atmosphere  should  be  moist 
enough  to  prevent  rapid  evaporation  from  the  surface  of 
the  beds.  Molds  and  foreign  fungi  may  develop  if  too 
high  humidity  is  maintained.  The  best  mushroom  houses 
are  provided  with  means  of  ventilation  by  which  tempera- 
tures may  be  regulated  and  the  humidity  of  the  houses 
controlled  to  a  great  extent. 

Mushrooms  require  a  certain  amount  of  soil  moisture, 
just  as  do  the  higher  classes  of  plants.  There  is  always 
some  daily  loss  of  moisture  from  the  beds  by  evaporation, 
and  the  harvesting  of  a  successful  crop  also  removes  a 
considerable  quantity  of  water.  Some  of  the  old  growers 
claimed  that  the  beds  should  never  be  watered  after  the 
mushrooms  began  to  appear,  and  no  doubt  this  was  often 
responsible  for  light  crops.  Drenching  and  over-water- 
ing should  be  carefully  avoided,  but  there  can  be  no 
doubt  about  the  value  or  necessity  of  light  sprinklings 
whenever  the  casing  seems  to  indicate  the  need  of  such 
treatment.  If  the  casing  is  kept  moist,  but  not  wet,  there 
will  be  no  danger  of  the  compost  or  manure  becoming 
too  dry.  Contrary  to  the  best  practice  in  vegetable  forc- 
ing, it  is  desirable  to  water  frequently  but  lightly,  but 
application  should  never  be  made  unless  there  is  assur- 
ance that  water  is  really  needed.  So  much  water  should 
never  be  applied  that  it  will  penetrate  the  casing  and  run 
into  the  manure,  for  this  invariably  weakens  the  my- 
celium, especially  in  the  early  stages  of  growth.  No  rule 
can  be  given  concerning  the  frequency  of  watering  any 
more  than  for  the  watering  of  greenhouse  crops. 

Temperature. — An  atmospheric  temperature  of  about 
55  degrees  is  considered  as  ideal  for  the  growing  of  mush- 


418  VEGETABLE  FORCING 


Fig.  153. — A  good  crop  of  mushrooms. 

rooms.  Growth  is  more  rapid  at  higher  temperatures, 
but  the  period  of  production  is  shorter  and  the  crop 
lighter.  Fair  results  are  possible  at  60  to  65  degrees,  and 
satisfactory  yields  may  be  obtained  when  the  tempera- 
ture is  about  50  degrees.  Low  temperatures  invariably 
prolong  the  period  of  production.  The  maintenance  of 
proper  temperatures  is  the  most  important  means  of  con- 
trolling insects  and  diseases. 

Light. — Light  is  not  injurious  to  the  growth  of  mush- 
rooms, for,  as  previously  stated,  they  are  often  grown 
under  the  benches  in  greenhouses  and  in  cellars  provided 
with  windows  without  any  attempt  to  screen  the  beds 
from  light.  It  is  indeed  an  advantage  to  have  some  day- 
light in  mushroom  houses,  though  artificial  lights  are 
generally  employed.  Large  windows  are  objectionable 
because  they  admit  sunlight  and  this  may  raise  the 
temperature  of  the  house  at  a  time  when  additional  heat 
would  be  disastrous  to  the  crop. 

Insect  enemies  may  appear  in  mushroom  houses, 
but  they  seldom  cause  serious  losses  when  proper 
sanitary  measures  are  observed.  It  is  very  impor- 
tant, however,  for  growers  to  be  alert,  for  insect 


MUSHROOMS  419 

pests  are  sometimes  responsible  for  total  crop  failures. 

Small  flies  or  gnats  of  various  descriptions  are  among 
the  most  common  pests.  They  are  invariably  present  in 
untreated  manure,  and  under  favorable  conditions  mul- 
tiply very  rapidly  and  soon  become  a  great  nuisance. 
High  temperatures  are  especially  favorable  for  the  breed- 
ing of  these  pests,  and  therefore  they  are  most  likely  to 
damage  mushrooms  in  beds  which  have  been  spawned 
early  in  the  autumn  or  before  the  advent  of  cold  weather, 
for  the  flies  are  practically  inactive  at  temperatures  below 
55  degrees.  The  damage  is  caused  by  the  larvae  of  mag- 
gots passing  up  through  the  stipes  and  riddling  the  caps. 
Fumigation  with  tobacco  (page  105)  at  the  strength  gener- 
ally employed  in  greenhouses  will  kill  the  adult  flies. 
Hydrocyanic  gas  (page  109)  may  be  employed  before  the 
beds  are  spawned.  Bulletin  155,  U.  S.  Bureau  of  Ento- 
mology, gives  a  description  and  life  history  of  the  various 
insects  which  feed  on  mushrooms. 

The  mushroom  mite  (Tyroglyphus  linteri)  is  always 
present  in  stable  manure,  and  it  may  cause  serious  dam- 
age to  the  crop  if  the  manure  has  not  been  properly 
composted.  It  multiplies  most  rapidly  at  high  tempera- 
tures and  in  dry  manure ;  this  is  an  important  reason  for 
maintaining  an  adequate  supply  of  moisture  in  the  com- 
post pile.  Apparently  there  is  no  practical  means  of 
eradicating  the  pests  when  they  appear  after  the  beds 
have  been  spawned.  They  feed  both  upon  the  spawns 
and  upon  the  mushrooms. 

Springtails  are  very  minute,  grayish-black  insects, 
which  sometimes  appear  in  great  numbers  upon  the  sur- 
face of  the  beds.  These  pests  are  most  likely  to  be 
troublesome  in  damp,  poorly  ventilated  houses  or  caves. 
They  generally  attack  the  mushrooms  through  the  gills. 
Thorough  ventilation,  applications  of  pyrethrum  powder, 
and  the  dusting  of  the  beds  and  floors  with  quicklime  are 
among  the  remedies  recommended. 


420  VEGETABLE  FORCING 

The  common  sowbug  is  also  an  enemy  of  the  mush- 
room. It  may  multiply  in  decaying  wood,  or  gain  an 
entrance  to  the  house  through  the  manure  or  compost. 
This  pest,  if  uncontrolled,  will  destroy  many  pounds  of 
mushrooms  in  a  very  short  time.  An  effective  remedy  is 
to  place  poisoned  slices  of  raw  potatoes  over  the  beds.  If 
only  a  few  sowbugs  appear,  a  little  handpicking  may  be 
all  that  is  required. 

Diseases. — Duggar  believes  it  highly  probable  that  the 
chief  types  of  disease  affecting  cultivated  mushrooms  are 
due  to  one  species,  Mycogone  perniciosa,  which  possesses 
two  spore  stages,  and  grows  upon  both  the  spawn  and  the 
mushrooms.  The  disease  causes  an  enlargement  of  all 
parts  of  the  mushroom,  and  usually  covers  it  with  a  mold- 
like  coating.  In  the  second  stage  of  the  disease,  the  stem 
is  greatly  enlarged  and  the  cap  poorly  developed.  In  this 
stage  the  mushrooms  are  very  soft,  and  often  decay  before 
they  attain  normal  size,  though  specimens  of  abnormal 
proportions  occur  in  diseased  beds.  A  2^  per  cent  solu- 
tion of  lysol  is  recommended  for  spraying  diseased  beds, 
though  fumigating  with  the  vapors  of  formaldehyde  is 
considered  more  effective.  See  "Mushroom  Growing," 
by  Duggar,  page  139. 

Diseases  and  insect  enemies  are  not  likely  to  cause 
serious  losses  in  the  growing  of  mushrooms  if  proper 
attention  is  given  to  sanitation.  The  soil,  compost  and 
lumber  should  be  removed  annually  and  all  interior  parts 
of  the  house  thoroughly  treated  for  the  destruction  of 
insect  pests  and  disease  germs. 

Picking  and  marketing. — The  beds  generally  begin  to 
produce  in  6  to  8  weeks  from  the  date  of  spawning, 
though  10  to  12  weeks  may  elapse,  if  the  temperatures  are 
abnormally  low  or  if  shavings  manure  has  been  used  for 
the  compost.  The  period  of  production  is  extremely  vari- 
able, but  it  should  continue  for  several  months. 

It  is  necessary  to  look  over  the  beds  every  day,  so  that 


MUSHROOMS 


421 


each  mushroom  will  be  picked  just  as  soon  at  it  attains 
the  desired  size.  If  a  fancy  price  can  be  obtained,  they 
may  be  picked  in  the  "button"  stage.  If  maximum 
weight  is  desired,  they  should  be  gathered  after  the  crop 
is  fully  expanded  but  before  the  veil  begins  to  break,  for 
there  will  be  no  increase  in  weight  beyond  this  time. 

As  a  rule  the  mushrooms  are  removed  by  giving  them  a 
twist,  although  cutting  is  sometimes  practiced ;  but  it  is 
thought  by  some  that  decay  is  more  likely  to  occur  if 
stubs  are  left  as  a  result  of  cutting  the  stems  instead  of 
breaking  them.  When  the  removal  of  one  or  more  mush- 
rooms from  a  cluster  leaves  a  depression  in  the  bed,  it 
should  be  filled  with  soil  such  as  was  used  for  the  casing. 
The  mushrooms  are  placed  in  shallow  trays  or  baskets 
and  taken  to  the  packing  room  where  the  ends  of  the 
stems  are  cut  smooth  before  the  mushrooms  are  packed. 


Fig.    154. — A    morning's    picking.      Note    variation    in    size. 

The  grower  should  never  lose  sight  of  the  fact  that  he  is 
producing  an  article  regarded  as  a  luxury  by  consumers, 
and  that  they  expect  to  pay  a  good  price,  in  return  for 
which  they  demand  the  highest  quality.  Careful  grading, 
therefore,  is  essential.  All  inferior  or  defective  specimens 


422  VEGETABLE  FORCING 

should  be  discarded,  and  two  or  more  grades  should  be 
made  of  those  that  are  marketable. 

Mushrooms  are  sold  in  a  great  diversity  of  packages. 
Boxes  or  carriers  and  baskets  of  various  descriptions  are 
in  common  use.  (See  Fig.  155.)  Baskets  holding  five  to 
ten  pounds  are  used,  but  four-pound  climax  baskets  are 
most  popular  and  the  product  carries  better  in  a  package 
of  this  size  than  it  does  in  larger  ones.  The  smaller 


Fig.    155. — Baskets  of  mushrooms   packed  ready  for  the  covers. 

packages  which  hold  only  one  or  two  pounds  are  gaming 
in  popularity.  They  should  be  lined  with  paper  and  made 
as  attractive  as  possible. 

Mushrooms  will  keep  in  good  condition  in  ordinary 
temperatures  for  two  days,  and  in  cold  storage  much 
longer.  It  is  desirable,  however,  to  market  them  as  soon 
as  possible  after  they  are  picked. 

Yields  and  prices. — Some  growers  consider  the  crop 
profitable  when  an  average  of  half  a  pound  of  mushrooms 
is  picked  per  square  foot,  but  the  beds  should  yield  a 
pound  to  the  square  foot,  and  two  pounds  are  often  re- 
ported. The  price  per  pound  varies  from  25  cents  to  $1, 


MUSHROOMS 


423 


though  the  latter  price  is  seldom  received.    A  gross  return 
of  30  cents  a  pound  is  probably  about  the  average. 

Food  value. — There  is  an  erroneous  impression  among 
many  people  that  the  mushroom  possesses  very  high 
nutritive  value.  Some  believe  that  it  is  equal  to  beef  in 
its  ability  to  form  muscle  or  to  impart  energy.  But  this 
assumption  is  far  from  the  truth,  for  round  beefsteak 
contains  18.7  per  cent  protein  while  the  common  mush- 
room, Agaricus  campestris,  contains  only  3.6  per  cent  pro- 
tein, about  the  same  amount  that  is  possessed  by  the  potato 
and  the  cabbage.  Both  cabbage  and  potatoes  contain  a  larger 
percentage  of  carbohy- 
drates, and  when  ex- 
pressed in  calories  the 
potato  possesses  more 
than  double  the  nutri- 
tive value  of  the  mush- 
room. But  these 
figures  are  not  given 
with  the  idea  of  mini- 
mizing the  importance 
of  the  mushroom  as  an 
article  of  food.  There 
is  a  difference  between 
nutritive  value  and 
food  value.  The  mush- 
room, when  properly 
cooked  and  served, 
possesses  such  a  deli- 
cious flavor  and  pleas- 
ant odor  that  it  ranks 
very  high  as  a  food, 
though  it  is  properly 
termed  a  luxury. 

Value  of  manure  from  mushroom  beds. — In  most  sec- 
tions of  the  country  the  manure  from  mushroom  houses 


Fig.    156. — A   wagon    load   of   mushrooms   en- 
route  to  shipping  station. 


424  VEGETABLE   FORCING 

is  used  for  the  forcing  of  vegetables  or  the  growing  of 
flowers.  A  fair  idea  of  its  fertilizing  value  is  given  by  a 
number  of  analyses  of  such  manures  made  at  the  Penn- 
sylvania Experiment  Station,  under  the  direction  of 
Frear.  For  comparison  the  average  of  a  number  of 
analyses  of  fresh  horse  manure,  with  litter,  is  added. 

ANALYSES  OF  MUSHROOM  MANURES  (Per  cent) 


Mushroom 
manures 
1 
2 
3 
4 
5 
6 
7 

Average 
Fresh  horse 
manure 

Moisture 

30.97 
4.45 
52.94 
45.52 
38.32 
57.05 
22.42 

Organic       Mineral 
matter         matter 
15.99            53.04 
25.31             70.24 
[          47.06          ] 
12.30             42.18 
30.10             31.58 
29.84             13.11 
40.12             37.46 

Nitrogen 

.626 
.80 
1.22 
.32 
1.21 
1.17 
1.60 

Potash 

.93 
1.47 
1.41 
.16 
.25 
.45 
.32 

Phosphoric 
acid 
.64 
.85 
1.14 
.26 
1.06 
1.05 
1.31 

33.12 
72.33 

25.61 
23.47 

41.27 
4.20 

.99 
.61 

.71 
.565 

.90 

.37 

Frear  says  of  these  analyses : 

"No  detailed  information  accompanied  the  first  four  samples. 
No.  5  represented  many  different  beds,  filled  with  manure  that  had 
been  watered  and  turned  three  to  five  times  before  benching;  No.  6, 
six  beds  filled  with  manure  that  was  well  rotted,  extremely  short 
and  very  wet  when  benched,  and  that  became  so  pasty  and  sticky 
that  it  had  to  be  turned  up  to  dry  before  spawning  was  attempted; 
No.  7,  manure  benched  directly  from  the  car,  in  a  very  wet  state,  and 
watered  heavily  two  or  three  times  before  spawning. 

"It  is  not  known,  in  any  instance,  whether  the  casing  earth  was 
at  all  separated  from  these  samples.  The  high  mineral  content,  at 
least  of  all  but  No.  6,  indicates  the  presence  of  such  earthy  admixture. 

"The  mushroom  manures  are  much  drier  than  the  fresh  stable 
manure.  This  accounts  in  part  for  their  comparative  concentration, 
but  only  in  part.  The  relative  composition  of  the  dry  matter  of  the 
fresh  horse  manure  and  of  the  average  for  the  seven  mushroom 
manures  shows : 

Horse  manure        Mushroom  manure 
per  cent  per  cent 

Organic  matter 84.60  40.37 

Mineral  matter 15.40  59.63 

Nitrogen 2.20  1.67 

Potash   2.04  1.15 

Phosphoric  acid 1.34  1.51 


MUSHROOMS  425 

"The  potash  in  the  mushroom  manure  is  relatively  low,  the 
phosphoric  acid  high,  as  compared  with  horse  manure.  The  mush- 
rooms do  use  much  more  of  potash  than  of  phosphoric  acid,  but 
their  consumption  is  very  small  in  proportion  to  the  supply  given. 
One  hundred  cubic  feet  of  manure,  underlying  100  square  feet  of 
the  beds,  would  weigh,  in  the  fresh  state,  and  compacted,  approxi- 
mately 3,500  pounds,  and  would  furnish  about  77  pounds  of  nitrogen, 
71  of  potash  and  47  of  phosphoric  acid.  One  hundred  pounds  of 
mushrooms  harvested  from  100  square  feet  of  beds  contain  only 
0.58  pounds  of  nitrogen,  0.23  of  potash  and  0.07  of  phosphoric  acid. 

"The  changes  the  horse  manure  undergoes,  during  its  preparation 
for  and  use  in  the  mushroom  beds,  are  little,  if  at  all  different,  from 
those  which  would  attend  its  quite  complete  rotting  under  other  con- 
ditions, with  the  exception  that  all  but  samples  Nos.  2  and  3  indicate 
some  loss  by  leaching  away  of  the  potash  either  during  composting 
or  at  some  earlier  time.  The  result  is  a  relative  depression  of  the 
soluble  potash  and,  in  some  measure,  of  nitrogen  and  a  correspond- 
ing increase  in  the  proportion  of  the  phosphoric  acid,  which  is  pres- 
ent in  forms  not  soluble  in  water. 

"All  in  all,  the  mushroom  manures  are  somewhat  richer  in  nitro- 
gen and  potash,  and  much  richer  in  phosphoric  acid  than  an  equal 
weight  of  fresh  horse  manure.  It  is  probable,  however,  that  their 
values  for  agricultural  use  are  like  those  of  other  well-rotted 
manures,  as  distinguished  from  fresh  manures  holding  the  soluble 
urinary  constituents  little  changed." 


INDEX 


Page 


Advertising     174 

Ammoniacal  copper   carbonate    . .   132 

Aphis     119 

Arsenate  of  lead    115 

Asparagus,   digging  roots    182 

forcing   in    permanent   beds..   183 

in    frames     396 

forcing  transplanted   roots    . .   186 

growing    roots     179 

importance    177 

marketing    189 

planting      188 

principles   in   culture    178 

size    of    roots    181 

storing    roots     182 

temperature    for    forcing    . . .   188 

varieties     179 

watering     188 


B 


Bean 


in    frames 


356 

335 

Beet 359 

in  frames  398 

Bordeaux    mixture     131 


Capital   required    8 

Carrot    360 

in    frames    399 

Cauliflower,    analysis    238 

beds    vs   benches    234 

cultivating      242 

diseases     242 

fertilizing     237 

frame    culture     243 

head   protection    243 

history     234 

importance     234 

in    frames    399 

insect  enemies   242 

intercropping     241 

marketing    243 

planting     241 

returns     245 

seed     235 

soil  preparation   239 

starting  plants    239 

temperature    242 

varieties     235 

ventilation     242 

watering    241 


Page 

Celery    352 

in  frames    400 

Chinese    cabbage    360 

in  frames    400 

Climatic    influences    11 

Commercial   fertilizers    66 

Companion    cropping    382 

Co-operative  associations    174 

Corn  salad   in   frames    400 

Cress    361 

in  frames    400 

Cucumber,      American-E  n  g  1  i  s  h 

crosses    305 

American    varieties    305 

anthracnose    339 

bacterial  wilt 340 

cultivation     320 

diseases    333 

English    varieties    302 

fertilizing    314 

frame  culture    336 

ground  beds  vs  benches   302 

history    300 

importance    300 

in  frames    400 

insect  enemies    337 

intercropping     336 

marketing    342 

mulching    320 

planting     3ig 

planting   distances    316 

pollination     329 

powdery    mildew    340 

pruning    324 

returns     344 

season    of   culture    300 

seed    306 

shading    .  .    324 

soil    314 

soil  preparation     315 

soil  temperature     322 

starting  plants    308 

temperature    321 

training     324 

varieties 302 

watering     318 

yields     344 


Damping-off   148 

Dandelion 364 

in  frames    402 

Diseases,    Bordeaux,    mixture    131 

control    127 

crop    rotation    131 

formalin   sterilization    131 


427 


428 


INDEX 


Page 

infected  plants   128 

influence   of   light    128 

influence  of  moisture 129" 

influence  of  temperature    ....   130 

manure    selection     128 

resistant  plants    131 

soil    selection     123 

spraying    131 

steam   sterilization    131 

summer   mulch    13] 

vigorous   plant   growth    130 


Economic    production    of    forcing 

crops     7 

Eggplant     385 

in  frames  403 


Fertilizers,    applying    84 

Flats    vs  beds    139 

Formalin      sterilization,      applica- 
tion          99 

cost    100 

strength  of  solution    98 


Frames,    heating    , 

Frames  vs  greenhouses 


Page 
.  393 
,  387 


Frame  crops 
asparagus 
bean    .... 
beet     .... 
carrot 


387 

396 

396 

398 

..   399 


cauliflower     399 

celery     400 

Chinese    cabbage    400 

cloth-covered    frames     389 

construction  of  frames 388 

control  of  pests    398 

.      corn    salad    400 

cress     400 

cucumber     400 

dandelion    402 

eggplant     403 

fertilizing     394 

importance     387 

kohl-rabi    403 

lettuce     403 

location  of  frames   388 

muskmelon     404 

mustard     405 

parsley     405 

pepper     403 

radish    405 

rhubarb    408 

Frame  crops,  sash-covered  frames  392 

spinach    406 

Swiss  chard    406 

turnips     408 

ventilation     395 

watering     395 

witloof    chicory     406 


Greenhouse    construction    13 

alleys    38 

arrangement  of  houses 16 

beds    and    benches    38 

braces     32 

doors     32 

eaves     28 

forms   of   houses    18 

frame     28 

glass 32 

glazing      34 

grading 14 

iron    construction    24 

materials     17 

posts     32 

purlins     32 

roof     29 

sash   bars    29 

semi-iron    construction     24 

side    plates     28 

size      and      proportion      of 

houses     14 

truss   construction    26 

ventilators     30 

walks    38 

walk     26 

wall    plate    28 

wood    construction    22 

Greenhouse    heating    39 

boiler    43 

location    of    pipes     43 

radiation    required     40 

Green    manuring    74 

Greenhouse,    painting     56 

sanitation    127 

temperature     163 

Gresnhouse  vs  frames    13 


H 


Harvesting    greenhouse   crops    . .  .   166 

Hot  water  heating      39,     40 

Hot  water  sterilization     101 

Hydrocyanic  gas   fumigation    ....   109 


I 


Insect   enemies    103 

control     103 

control    by    hydrocyanic    gas 

fumigation      109 

control     by     steam     steriliza- 
tion    104 

control    by    tobacco     fumiga- 
tion        105 


INDEX 


429 


Page 

control    by    tobacco   prepara- 
tions      108 

preventive  measures    103 

rotation   of   crops    104 

Insecticides,   miscellaneous    115 


Kerosene   emulsion    115 

Kohl-rabi   366 

in    frames    403 


Lettuce,  beds  vs  benches  206 

cultivation  222 

diseases  225 

electro-culture  227 

fertilizing  211 

frame  culture  222 

harvesting  227 

importance  204 

in  frames  403 

insect  enemies  224 

intercropping 222 

marketing  230 

planting  218 

planting  distances  216 

pot  culture  222 

preparation  of  soil  213 

quality  205 

returns  232 

seed  209 

soil  210 

starting  plants  214 

temperature  220 

varieties  207 

ventilation  ,....  221 

watering  219 

yields  232 

Lime,  applying  83 

functions  64 

Location   for  vegetable  forcing    .       9 


M 


Manures  58 

cow  62 

horse  62 

liquid  64 

poultry  63 

rate  of  application  63 

Rhode  Island  experiments  . .  60 

sheep  62 

value  58 

Marketing  165 

advertising  174 

co-operative  associations  . . .  174 
delivery  trucks  and  wagons  .  172 

harvesting  croos  165 

methods  of  selling  172 

packing  170 


Page 

packages     168 

packing    room     167 

pre-cooling     174 

preparing    vegetables    169 

psychology    165 

refrigeration    174 

Mats    393 

Mints 366 

Muck    soils    53 

Mushrooms,    botanical    character- 
istics       408 

casing   beds    416 

diseases      ,..  420 

food   value   423 

importance     407 

insect   enemies    418 

light     418 

marketing     420 

material  for  beds    411 

moisture    conditions 417 

picking     420 

prices     422 

spawning    the   beds     416 

temperature     417 

value  of  manure  from  beds  .  423 

yields     422 

Muskmelon    diseases    354 

fertilizing     350 

house    347 

importance     346 

in    frames    404 

insect    enemies    354 

marketing     355 

pollinating    352 

size  of   fruit   354 

soil 348 

soil  preparation    350 

starting  plants    348 

temperature     352 

training     352 

varieties     347 

ventilation     j. .  354 

watering    351 

yields     354 

Mustard     367 

in  frames   ,. . . .  405 


N 

Nematodes     116 

Nitrogen,    sources    67 


Onion     367 

in  frames    405 

Outlook   for  vegetable  forcing   ..  12 

Overhead    irrigation    160 


430 


INDEX 


Page 


Packages  168 

Packing  room  167 

Painting  greenhouses  36 

Parsley  369 

in  frames  405 

Pea  339 

Pepper  370 

in  frames  405 

Phosphoric  acid,  sources  69 

Plant  food,  need  58 

Potassium  sulphide  133 

Potash,  sources  69 

Pots,  use  141 

Profits  in  vegetable  forcing  9 


Quality  of  greenhouse    vegetables       7 


Radish,   beds   vs   benches    247 

cultivation     257 

enemies     257 

fertilizing     , 248 

frame  culture    257 

importance     246 

in    frames     405 

intercropping      255 

light     246 

marketing     257 

returns     258 

seed     249 

soil     248 

soil   preparation    249 

sowing 254 

temperature    257 

thinning     255 

varieties     247 

ventilation    257 

watering     256 

yields    258 

Red    spider    • 123 

Refrigeration     174 

Rhizoctonia     77 

Rhubarb,    digging   roots    199 

forcing  in  permanent  beds    . .  192 
forcing   transplanted   roots    .   194 

freezing  roots    199 

growing  roots   197 

harvesting     201 

importance     190 

in    frames    406 

light    for    forcing    190 

marketing     201 

planting     200 

preparing    beds     199 

principles  in   forcing    191 

quality   190 

returns     202 


Page 

storing    roots    199 

temperature     200 

varieties     196 

watering     200 

yields     202 


Sea    kale 371 

Selection   of    crops    380 

Shading 164 

Shading    greenhouses    36 

Shutters     393 

Single   cropping    381 

Soils,    adaptation    57 

advantages  of  sandy    49 

Ashtabuia 55 

Boston  district 54 

chemical    composition    52 

Chester  fine  sandy  loam   ....     54 

classification     48 

Cleveland    56 

color     j 52 

depth    53 

drainage     53 

greenhouse    abnormal     46 

Irondequoit     57 

Lansdale  silt   loam    53 

muck    53 

Norfolk    series     57 

organic   content    52 

selection     46 

structure     51 

texture     46 

Toledo     56 

water  content   52 

Soil    preparation    70 

changing     70 

composting     71 

drying    76 

green   manuring    74 

harrowing    82 

manuring  in  the  field   73 

manuring    in    the  greenhouse     75 

plowing    82 

raking     83 

spading     83 

summer  mulching    78 

Soil    sterilization 85 

methods     , . . .     86 

necessity     85 

Spinach 372 

in  frames   406 

Spraying   apparatus    115 

Starting    plants    134 

care    148 

damping-off    148 

high    quality    134 

seed    of    high    quality     134 

seed  sowing    145 

separate   houses    137 

soil  preparation    144 

soil    selection     144 


INDEX 


431 


Page 

transplanting  146 

use  of  pots  141 

Steam    heating    39,     42 

Steam  sterilization    89 

after-treatment     98 

boiler     91 

boiler  pressure    91 

boxes    92 

devices    92 

frequency    97 

pans     93 

perforated    pegs    96 

perforated    pipe    95 

preparing  soil    92 

time   required    90 

Sub-irrigation      155 

Swiss    chard    373 

in    frames     406 

Succession    cropping    382 

plans     382 

Systems  of   cropping    379 


Thermostats     44 

Tobacco   fumigation    105 

Tobacco  preparations    108 

Tomato,    Alternavia    solani     295 

benches    vs    beds    262 

blossom-end    rot    293 

boxes 262 

cultivation     286 

cuttings     275 

diseases     292 

fertilizing     272 

history     250 

importance    260 

insects    292 

intercropping     280 

leaf  blight    295 

leaf  spot    295 

marketing     296 

mulching 286 

planting     280 

planting    distances     279 


Page 

pollinating    288 

pots     262 

returns     295 

seed     275 

soil     271 

soil    preparation     274 

starting    plants     276 

temperature    285 

training     280 

varieties     265 

ventilation      286 

watering     284 

yields    298 

Transplanting     146 

Trucks     , 172 

Turnip     373 

in    frames    406 


Vegetable  forcing 1 

history  1 

importance  4,  12 

organization  5 

prominent  sections  2 

southern  competition  6 

Ventilation     163 


w 

Wagons     172 

Water,    amount    150 

importance     149 

temperature     153 

Watering     149 

methods     153 

overhead    irrigation     160 

sub-irrigation      155 

use   of    can    154 

use  of  hose    154 

when     151 

White  fly    120 

Witloof   chicory    373 

in    frames    406 


6UJ6J 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


(SLf 


